diff --git a/server/src/creators/thread-creator.js b/server/src/creators/thread-creator.js
index 5f7eecf31..0d22a1f79 100644
--- a/server/src/creators/thread-creator.js
+++ b/server/src/creators/thread-creator.js
@@ -1,369 +1,377 @@
 // @flow
 
 import invariant from 'invariant';
 
 import {
   generatePendingThreadColor,
   generateRandomColor,
 } from 'lib/shared/thread-utils';
 import { hasMinCodeVersion } from 'lib/shared/version-utils';
 import { messageTypes } from 'lib/types/message-types';
 import { userRelationshipStatus } from 'lib/types/relationship-types';
 import {
   type NewThreadRequest,
   type NewThreadResponse,
   threadTypes,
   threadPermissions,
 } from 'lib/types/thread-types';
 import { ServerError } from 'lib/utils/errors';
 import { promiseAll } from 'lib/utils/promises';
 
 import { dbQuery, SQL } from '../database/database';
 import { fetchThreadInfos } from '../fetchers/thread-fetchers';
 import { checkThreadPermission } from '../fetchers/thread-permission-fetchers';
 import { fetchKnownUserInfos } from '../fetchers/user-fetchers';
 import type { Viewer } from '../session/viewer';
 import {
   changeRole,
   recalculateAllPermissions,
   commitMembershipChangeset,
   setJoinsToUnread,
   getRelationshipRowsForUsers,
   getParentThreadRelationshipRowsForNewUsers,
 } from '../updaters/thread-permission-updaters';
 import createIDs from './id-creator';
 import createMessages from './message-creator';
 import { createInitialRolesForNewThread } from './role-creator';
 import type { UpdatesForCurrentSession } from './update-creator';
 
 // If forceAddMembers is set, we will allow the viewer to add random users who
 // they aren't friends with. We will only fail if the viewer is trying to add
 // somebody who they have blocked or has blocked them. On the other hand, if
 // forceAddMembers is not set, we will fail if the viewer tries to add somebody
 // who they aren't friends with and doesn't have a membership row with a
 // nonnegative role for the parent thread.
 async function createThread(
   viewer: Viewer,
   request: NewThreadRequest,
   forceAddMembers?: boolean = false,
   updatesForCurrentSession?: UpdatesForCurrentSession = 'return',
 ): Promise<NewThreadResponse> {
   if (!viewer.loggedIn) {
     throw new ServerError('not_logged_in');
   }
 
   const threadType = request.type;
   const shouldCreateRelationships =
     forceAddMembers || threadType === threadTypes.PERSONAL;
   const parentThreadID = request.parentThreadID ? request.parentThreadID : null;
   const initialMemberIDs =
     request.initialMemberIDs && request.initialMemberIDs.length > 0
       ? request.initialMemberIDs
       : null;
 
   if (
     threadType !== threadTypes.CHAT_SECRET &&
     threadType !== threadTypes.PERSONAL &&
     !parentThreadID
   ) {
     throw new ServerError('invalid_parameters');
   }
 
   if (
     threadType === threadTypes.PERSONAL &&
     (request.initialMemberIDs?.length !== 1 || parentThreadID)
   ) {
     throw new ServerError('invalid_parameters');
   }
 
   const checkPromises = {};
   if (parentThreadID) {
     checkPromises.parentThreadFetch = fetchThreadInfos(
       viewer,
       SQL`t.id = ${parentThreadID}`,
     );
     checkPromises.hasParentPermission = checkThreadPermission(
       viewer,
       parentThreadID,
       threadType === threadTypes.SIDEBAR
         ? threadPermissions.CREATE_SIDEBARS
         : threadPermissions.CREATE_SUBTHREADS,
     );
   }
   if (initialMemberIDs) {
     checkPromises.fetchInitialMembers = fetchKnownUserInfos(
       viewer,
       initialMemberIDs,
     );
   }
   const {
     parentThreadFetch,
     hasParentPermission,
     fetchInitialMembers,
   } = await promiseAll(checkPromises);
 
   let parentThreadMembers;
   if (parentThreadID) {
     invariant(parentThreadFetch, 'parentThreadFetch should be set');
     const parentThreadInfo = parentThreadFetch.threadInfos[parentThreadID];
     if (!hasParentPermission) {
       throw new ServerError('invalid_credentials');
     }
     parentThreadMembers = parentThreadInfo.members.map(
       (userInfo) => userInfo.id,
     );
   }
 
   const viewerNeedsRelationshipsWith = [];
   if (fetchInitialMembers) {
     invariant(initialMemberIDs, 'should be set');
     for (const initialMemberID of initialMemberIDs) {
       const initialMember = fetchInitialMembers[initialMemberID];
-      if (!initialMember && shouldCreateRelationships) {
+      if (
+        !initialMember &&
+        shouldCreateRelationships &&
+        (threadType !== threadTypes.SIDEBAR ||
+          parentThreadMembers?.includes(initialMemberID))
+      ) {
         viewerNeedsRelationshipsWith.push(initialMemberID);
         continue;
       } else if (!initialMember) {
         throw new ServerError('invalid_credentials');
       }
       const { relationshipStatus } = initialMember;
-      if (relationshipStatus === userRelationshipStatus.FRIEND) {
+      if (
+        relationshipStatus === userRelationshipStatus.FRIEND &&
+        threadType !== threadTypes.SIDEBAR
+      ) {
         continue;
       } else if (
         relationshipStatus === userRelationshipStatus.BLOCKED_BY_VIEWER ||
         relationshipStatus === userRelationshipStatus.BLOCKED_VIEWER ||
         relationshipStatus === userRelationshipStatus.BOTH_BLOCKED
       ) {
         throw new ServerError('invalid_credentials');
       } else if (
         parentThreadMembers &&
         parentThreadMembers.includes(initialMemberID)
       ) {
         continue;
       } else if (!shouldCreateRelationships) {
         throw new ServerError('invalid_credentials');
       }
     }
   }
 
   const [id] = await createIDs('threads', 1);
   const newRoles = await createInitialRolesForNewThread(id, threadType);
 
   const name = request.name ? request.name : null;
   const description = request.description ? request.description : null;
   let color = request.color
     ? request.color.toLowerCase()
     : generateRandomColor();
   if (threadType === threadTypes.PERSONAL) {
     color = generatePendingThreadColor(
       request.initialMemberIDs ?? [],
       viewer.id,
     );
   }
   const time = Date.now();
 
   const row = [
     id,
     threadType,
     name,
     description,
     viewer.userID,
     time,
     color,
     parentThreadID,
     newRoles.default.id,
   ];
   if (threadType === threadTypes.PERSONAL) {
     const otherMemberID = initialMemberIDs?.[0];
     invariant(
       otherMemberID,
       'Other member id should be set for a PERSONAL thread',
     );
     const query = SQL`
       INSERT INTO threads(id, type, name, description, creator,
         creation_time, color, parent_thread_id, default_role)
       SELECT ${row}
       WHERE NOT EXISTS (
         SELECT * 
         FROM threads t
         INNER JOIN memberships m1 
           ON m1.thread = t.id AND m1.user = ${viewer.userID}
         INNER JOIN memberships m2
           ON m2.thread = t.id AND m2.user = ${otherMemberID}
         WHERE t.type = ${threadTypes.PERSONAL}
           AND m1.role != -1
           AND m2.role != -1
       )
     `;
     const [result] = await dbQuery(query);
 
     if (result.affectedRows === 0) {
       const personalThreadQuery = SQL`
         SELECT t.id 
         FROM threads t
         INNER JOIN memberships m1 
           ON m1.thread = t.id AND m1.user = ${viewer.userID}
         INNER JOIN memberships m2
           ON m2.thread = t.id AND m2.user = ${otherMemberID}
         WHERE t.type = ${threadTypes.PERSONAL}
           AND m1.role != -1
           AND m2.role != -1
       `;
       const deleteRoles = SQL`
         DELETE FROM roles
         WHERE id IN (${newRoles.default.id}, ${newRoles.creator.id})
       `;
       const deleteIDs = SQL`
         DELETE FROM ids
         WHERE id IN (${id}, ${newRoles.default.id}, ${newRoles.creator.id})
       `;
       const [[personalThreadResult]] = await Promise.all([
         dbQuery(personalThreadQuery),
         dbQuery(deleteRoles),
         dbQuery(deleteIDs),
       ]);
       invariant(
         personalThreadResult.length > 0,
         'PERSONAL thread should exist',
       );
       const personalThreadID = personalThreadResult[0].id.toString();
 
       return {
         newThreadID: personalThreadID,
         updatesResult: {
           newUpdates: [],
         },
         userInfos: {},
         newMessageInfos: [],
       };
     }
   } else {
     const query = SQL`
       INSERT INTO threads(id, type, name, description, creator,
         creation_time, color, parent_thread_id, default_role)
       VALUES ${[row]}
     `;
     await dbQuery(query);
   }
 
   const [
     creatorChangeset,
     initialMembersChangeset,
     recalculatePermissionsChangeset,
   ] = await Promise.all([
     changeRole(id, [viewer.userID], newRoles.creator.id),
     initialMemberIDs ? changeRole(id, initialMemberIDs, null) : undefined,
     recalculateAllPermissions(id, threadType),
   ]);
 
   if (!creatorChangeset) {
     throw new ServerError('unknown_error');
   }
   const {
     membershipRows: creatorMembershipRows,
     relationshipRows: creatorRelationshipRows,
   } = creatorChangeset;
 
   const initialMemberAndCreatorIDs = initialMemberIDs
     ? [...initialMemberIDs, viewer.userID]
     : [viewer.userID];
   const {
     membershipRows: recalculateMembershipRows,
     relationshipRows: recalculateRelationshipRows,
   } = recalculatePermissionsChangeset;
 
   const membershipRows = [
     ...creatorMembershipRows,
     ...recalculateMembershipRows,
   ];
   const relationshipRows = [
     ...creatorRelationshipRows,
     ...recalculateRelationshipRows,
   ];
   if (initialMemberIDs) {
     if (!initialMembersChangeset) {
       throw new ServerError('unknown_error');
     }
     relationshipRows.push(
       ...getRelationshipRowsForUsers(
         viewer.userID,
         viewerNeedsRelationshipsWith,
       ),
     );
     const {
       membershipRows: initialMembersMembershipRows,
       relationshipRows: initialMembersRelationshipRows,
     } = initialMembersChangeset;
     const parentRelationshipRows = getParentThreadRelationshipRowsForNewUsers(
       id,
       recalculateMembershipRows,
       initialMemberAndCreatorIDs,
     );
     membershipRows.push(...initialMembersMembershipRows);
     relationshipRows.push(
       ...initialMembersRelationshipRows,
       ...parentRelationshipRows,
     );
   }
   setJoinsToUnread(membershipRows, viewer.userID, id);
 
   const changeset = { membershipRows, relationshipRows };
   const {
     threadInfos,
     viewerUpdates,
     userInfos,
   } = await commitMembershipChangeset(viewer, changeset, {
     updatesForCurrentSession,
   });
 
   const messageDatas = [
     {
       type: messageTypes.CREATE_THREAD,
       threadID: id,
       creatorID: viewer.userID,
       time,
       initialThreadState: {
         type: threadType,
         name,
         parentThreadID,
         color,
         memberIDs: initialMemberAndCreatorIDs,
       },
     },
   ];
   if (parentThreadID) {
     messageDatas.push({
       type: messageTypes.CREATE_SUB_THREAD,
       threadID: parentThreadID,
       creatorID: viewer.userID,
       time,
       childThreadID: id,
     });
   }
   const newMessageInfos = await createMessages(
     viewer,
     messageDatas,
     updatesForCurrentSession,
   );
 
   if (hasMinCodeVersion(viewer.platformDetails, 62)) {
     return {
       newThreadID: id,
       updatesResult: {
         newUpdates: viewerUpdates,
       },
       userInfos,
       newMessageInfos,
     };
   }
 
   return {
     newThreadInfo: threadInfos[id],
     updatesResult: {
       newUpdates: viewerUpdates,
     },
     userInfos,
     newMessageInfos,
   };
 }
 
 export default createThread;
diff --git a/server/src/updaters/thread-updaters.js b/server/src/updaters/thread-updaters.js
index 419427c94..1ac465a1e 100644
--- a/server/src/updaters/thread-updaters.js
+++ b/server/src/updaters/thread-updaters.js
@@ -1,706 +1,708 @@
 // @flow
 
 import invariant from 'invariant';
 
 import { filteredThreadIDs } from 'lib/selectors/calendar-filter-selectors';
 import {
   threadHasAdminRole,
   roleIsAdminRole,
   viewerIsMember,
 } from 'lib/shared/thread-utils';
 import { hasMinCodeVersion } from 'lib/shared/version-utils';
 import { messageTypes, defaultNumberPerThread } from 'lib/types/message-types';
 import { userRelationshipStatus } from 'lib/types/relationship-types';
 import {
   type RoleChangeRequest,
   type ChangeThreadSettingsResult,
   type RemoveMembersRequest,
   type LeaveThreadRequest,
   type LeaveThreadResult,
   type UpdateThreadRequest,
   type ServerThreadJoinRequest,
   type ThreadJoinResult,
   threadPermissions,
   threadTypes,
   assertThreadType,
 } from 'lib/types/thread-types';
 import { updateTypes } from 'lib/types/update-types';
 import { ServerError } from 'lib/utils/errors';
 import { promiseAll } from 'lib/utils/promises';
 
 import createMessages from '../creators/message-creator';
 import { createUpdates } from '../creators/update-creator';
 import { dbQuery, SQL } from '../database/database';
 import { fetchEntryInfos } from '../fetchers/entry-fetchers';
 import { fetchMessageInfos } from '../fetchers/message-fetchers';
 import { fetchThreadInfos } from '../fetchers/thread-fetchers';
 import {
   checkThreadPermission,
   viewerIsMember as fetchViewerIsMember,
   checkThread,
 } from '../fetchers/thread-permission-fetchers';
 import {
   verifyUserIDs,
   verifyUserOrCookieIDs,
   fetchKnownUserInfos,
 } from '../fetchers/user-fetchers';
 import type { Viewer } from '../session/viewer';
 import { updateRoles } from './role-updaters';
 import {
   changeRole,
   recalculateAllPermissions,
   commitMembershipChangeset,
   setJoinsToUnread,
   getParentThreadRelationshipRowsForNewUsers,
 } from './thread-permission-updaters';
 
 async function updateRole(
   viewer: Viewer,
   request: RoleChangeRequest,
 ): Promise<ChangeThreadSettingsResult> {
   if (!viewer.loggedIn) {
     throw new ServerError('not_logged_in');
   }
 
   const [memberIDs, hasPermission] = await Promise.all([
     verifyUserIDs(request.memberIDs),
     checkThreadPermission(
       viewer,
       request.threadID,
       threadPermissions.CHANGE_ROLE,
     ),
   ]);
   if (memberIDs.length === 0) {
     throw new ServerError('invalid_parameters');
   }
   if (!hasPermission) {
     throw new ServerError('invalid_credentials');
   }
 
   const query = SQL`
     SELECT user, role
     FROM memberships
     WHERE user IN (${memberIDs}) AND thread = ${request.threadID}
   `;
   const [result] = await dbQuery(query);
 
   let nonMemberUser = false;
   let numResults = 0;
   for (let row of result) {
     if (row.role <= 0) {
       nonMemberUser = true;
       break;
     }
     numResults++;
   }
   if (nonMemberUser || numResults < memberIDs.length) {
     throw new ServerError('invalid_parameters');
   }
 
   const changeset = await changeRole(request.threadID, memberIDs, request.role);
   if (!changeset) {
     throw new ServerError('unknown_error');
   }
   const { threadInfos, viewerUpdates } = await commitMembershipChangeset(
     viewer,
     changeset,
   );
 
   const messageData = {
     type: messageTypes.CHANGE_ROLE,
     threadID: request.threadID,
     creatorID: viewer.userID,
     time: Date.now(),
     userIDs: memberIDs,
     newRole: request.role,
   };
   const newMessageInfos = await createMessages(viewer, [messageData]);
 
   if (hasMinCodeVersion(viewer.platformDetails, 62)) {
     return { updatesResult: { newUpdates: viewerUpdates }, newMessageInfos };
   }
 
   return {
     threadInfo: threadInfos[request.threadID],
     threadInfos,
     updatesResult: {
       newUpdates: viewerUpdates,
     },
     newMessageInfos,
   };
 }
 
 async function removeMembers(
   viewer: Viewer,
   request: RemoveMembersRequest,
 ): Promise<ChangeThreadSettingsResult> {
   const viewerID = viewer.userID;
   if (request.memberIDs.includes(viewerID)) {
     throw new ServerError('invalid_parameters');
   }
 
   const [memberIDs, hasPermission] = await Promise.all([
     verifyUserOrCookieIDs(request.memberIDs),
     checkThreadPermission(
       viewer,
       request.threadID,
       threadPermissions.REMOVE_MEMBERS,
     ),
   ]);
   if (memberIDs.length === 0) {
     throw new ServerError('invalid_parameters');
   }
   if (!hasPermission) {
     throw new ServerError('invalid_credentials');
   }
 
   const query = SQL`
     SELECT m.user, m.role, t.default_role
     FROM memberships m
     LEFT JOIN threads t ON t.id = m.thread
     WHERE m.user IN (${memberIDs}) AND m.thread = ${request.threadID}
   `;
   const [result] = await dbQuery(query);
 
   let nonDefaultRoleUser = false;
   const actualMemberIDs = [];
   for (let row of result) {
     if (row.role <= 0) {
       continue;
     }
     actualMemberIDs.push(row.user.toString());
     if (row.role !== row.default_role) {
       nonDefaultRoleUser = true;
     }
   }
 
   if (nonDefaultRoleUser) {
     const hasChangeRolePermission = await checkThreadPermission(
       viewer,
       request.threadID,
       threadPermissions.CHANGE_ROLE,
     );
     if (!hasChangeRolePermission) {
       throw new ServerError('invalid_credentials');
     }
   }
 
   const changeset = await changeRole(request.threadID, actualMemberIDs, 0);
   if (!changeset) {
     throw new ServerError('unknown_error');
   }
   const { threadInfos, viewerUpdates } = await commitMembershipChangeset(
     viewer,
     changeset,
   );
 
   const messageData = {
     type: messageTypes.REMOVE_MEMBERS,
     threadID: request.threadID,
     creatorID: viewerID,
     time: Date.now(),
     removedUserIDs: actualMemberIDs,
   };
   const newMessageInfos = await createMessages(viewer, [messageData]);
 
   if (hasMinCodeVersion(viewer.platformDetails, 62)) {
     return { updatesResult: { newUpdates: viewerUpdates }, newMessageInfos };
   }
 
   return {
     threadInfo: threadInfos[request.threadID],
     threadInfos,
     updatesResult: {
       newUpdates: viewerUpdates,
     },
     newMessageInfos,
   };
 }
 
 async function leaveThread(
   viewer: Viewer,
   request: LeaveThreadRequest,
 ): Promise<LeaveThreadResult> {
   if (!viewer.loggedIn) {
     throw new ServerError('not_logged_in');
   }
 
   const [fetchThreadResult, hasPermission] = await Promise.all([
     fetchThreadInfos(viewer, SQL`t.id = ${request.threadID}`),
     checkThreadPermission(
       viewer,
       request.threadID,
       threadPermissions.LEAVE_THREAD,
     ),
   ]);
 
   const threadInfo = fetchThreadResult.threadInfos[request.threadID];
   if (!viewerIsMember(threadInfo) || !hasPermission) {
     throw new ServerError('invalid_parameters');
   }
 
   const viewerID = viewer.userID;
   if (threadHasAdminRole(threadInfo)) {
     let otherUsersExist = false;
     let otherAdminsExist = false;
     for (let member of threadInfo.members) {
       const role = member.role;
       if (!role || member.id === viewerID) {
         continue;
       }
       otherUsersExist = true;
       if (roleIsAdminRole(threadInfo.roles[role])) {
         otherAdminsExist = true;
         break;
       }
     }
     if (otherUsersExist && !otherAdminsExist) {
       throw new ServerError('invalid_parameters');
     }
   }
 
   const changeset = await changeRole(request.threadID, [viewerID], 0);
   if (!changeset) {
     throw new ServerError('unknown_error');
   }
   const { threadInfos, viewerUpdates } = await commitMembershipChangeset(
     viewer,
     changeset,
   );
 
   const messageData = {
     type: messageTypes.LEAVE_THREAD,
     threadID: request.threadID,
     creatorID: viewerID,
     time: Date.now(),
   };
   await createMessages(viewer, [messageData]);
 
   if (hasMinCodeVersion(viewer.platformDetails, 62)) {
     return { updatesResult: { newUpdates: viewerUpdates } };
   }
 
   return {
     threadInfos,
     updatesResult: {
       newUpdates: viewerUpdates,
     },
   };
 }
 
 async function updateThread(
   viewer: Viewer,
   request: UpdateThreadRequest,
 ): Promise<ChangeThreadSettingsResult> {
   if (!viewer.loggedIn) {
     throw new ServerError('not_logged_in');
   }
 
   const validationPromises = {};
 
   const changedFields = {};
   const sqlUpdate = {};
   const { name } = request.changes;
   if (name !== undefined && name !== null) {
     changedFields.name = name;
     sqlUpdate.name = name ?? null;
   }
   const { description } = request.changes;
   if (description !== undefined && description !== null) {
     changedFields.description = description;
     sqlUpdate.description = description ?? null;
   }
   if (request.changes.color) {
     const color = request.changes.color.toLowerCase();
     changedFields.color = color;
     sqlUpdate.color = color;
   }
   const { parentThreadID } = request.changes;
   if (parentThreadID !== undefined) {
     // TODO some sort of message when this changes
     sqlUpdate.parent_thread_id = parentThreadID;
   }
 
   const threadType = request.changes.type;
   if (threadType !== null && threadType !== undefined) {
     changedFields.type = threadType;
     sqlUpdate.type = threadType;
   }
 
   if (threadType === threadTypes.PERSONAL) {
     throw new ServerError('invalid_parameters');
   }
 
   const newMemberIDs =
     request.changes.newMemberIDs && request.changes.newMemberIDs.length > 0
       ? [...request.changes.newMemberIDs]
       : null;
 
   if (Object.keys(sqlUpdate).length === 0 && !newMemberIDs) {
     throw new ServerError('invalid_parameters');
   }
 
   if (newMemberIDs) {
     validationPromises.fetchNewMembers = fetchKnownUserInfos(
       viewer,
       newMemberIDs,
     );
   }
 
   const validationQuery = SQL`
     SELECT type, parent_thread_id
     FROM threads
     WHERE id = ${request.threadID}
   `;
   validationPromises.validationQuery = dbQuery(validationQuery);
 
   const checks = [];
   if (
     sqlUpdate.name !== undefined ||
     sqlUpdate.description !== undefined ||
     sqlUpdate.color !== undefined
   ) {
     checks.push({
       check: 'permission',
       permission: threadPermissions.EDIT_THREAD,
     });
   }
   if (parentThreadID !== undefined || sqlUpdate.type !== undefined) {
     checks.push({
       check: 'permission',
       permission: threadPermissions.EDIT_PERMISSIONS,
     });
   }
   if (newMemberIDs) {
     checks.push({
       check: 'permission',
       permission: threadPermissions.ADD_MEMBERS,
     });
   }
 
   validationPromises.hasNecessaryPermissions = checkThread(
     viewer,
     request.threadID,
     checks,
   );
 
   const {
     fetchNewMembers,
     validationQuery: [validationResult],
     hasNecessaryPermissions,
   } = await promiseAll(validationPromises);
 
   if (validationResult.length === 0) {
     throw new ServerError('internal_error');
   }
   const validationRow = validationResult[0];
 
   if (!hasNecessaryPermissions) {
     throw new ServerError('invalid_credentials');
   }
 
   const oldThreadType = assertThreadType(validationRow.type);
   const oldParentThreadID = validationRow.parent_thread_id
     ? validationRow.parent_thread_id.toString()
     : null;
 
   const nextThreadType =
     threadType !== null && threadType !== undefined
       ? threadType
       : oldThreadType;
   const nextParentThreadID =
     parentThreadID !== undefined ? parentThreadID : oldParentThreadID;
 
   // If the thread is being switched to nested, a parent must be specified
   if (
     oldThreadType === threadTypes.CHAT_SECRET &&
     threadType !== undefined &&
     threadType !== null &&
     threadType !== threadTypes.CHAT_SECRET &&
     nextParentThreadID === null
   ) {
     throw new ServerError('no_parent_thread_specified');
   }
 
   let parentThreadMembers;
   if (nextParentThreadID) {
     const promises = [
       fetchThreadInfos(viewer, SQL`t.id = ${nextParentThreadID}`),
     ];
 
     const threadChanged =
       nextParentThreadID !== oldParentThreadID ||
       nextThreadType !== oldThreadType;
     if (threadChanged) {
       promises.push(
         checkThreadPermission(
           viewer,
           nextParentThreadID,
           nextThreadType === threadTypes.SIDEBAR
             ? threadPermissions.CREATE_SIDEBARS
             : threadPermissions.CREATE_SUBTHREADS,
         ),
       );
     }
 
     const [parentFetchResult, hasParentPermission] = await Promise.all(
       promises,
     );
 
     const parentThreadInfo = parentFetchResult.threadInfos[nextParentThreadID];
     if (!parentThreadInfo) {
       throw new ServerError('invalid_parameters');
     }
     if (threadChanged && !hasParentPermission) {
       throw new ServerError('invalid_parameters');
     }
     parentThreadMembers = parentThreadInfo.members.map(
       (userInfo) => userInfo.id,
     );
   }
 
   if (fetchNewMembers) {
     invariant(newMemberIDs, 'should be set');
     for (const newMemberID of newMemberIDs) {
       if (!fetchNewMembers[newMemberID]) {
         throw new ServerError('invalid_credentials');
       }
       const { relationshipStatus } = fetchNewMembers[newMemberID];
-
-      if (relationshipStatus === userRelationshipStatus.FRIEND) {
+      if (
+        relationshipStatus === userRelationshipStatus.FRIEND &&
+        nextThreadType !== threadTypes.SIDEBAR
+      ) {
         continue;
       } else if (
         parentThreadMembers &&
         parentThreadMembers.includes(newMemberID) &&
         relationshipStatus !== userRelationshipStatus.BLOCKED_BY_VIEWER &&
         relationshipStatus !== userRelationshipStatus.BLOCKED_VIEWER &&
         relationshipStatus !== userRelationshipStatus.BOTH_BLOCKED
       ) {
         continue;
       }
       throw new ServerError('invalid_credentials');
     }
   }
 
   const intermediatePromises = {};
   if (Object.keys(sqlUpdate).length > 0) {
     const updateQuery = SQL`
       UPDATE threads SET ${sqlUpdate} WHERE id = ${request.threadID}
     `;
     intermediatePromises.updateQuery = dbQuery(updateQuery);
   }
   if (newMemberIDs) {
     intermediatePromises.addMembersChangeset = changeRole(
       request.threadID,
       newMemberIDs,
       null,
     );
   }
   if (
     nextThreadType !== oldThreadType ||
     nextParentThreadID !== oldParentThreadID
   ) {
     intermediatePromises.recalculatePermissionsChangeset = (async () => {
       if (nextThreadType !== oldThreadType) {
         await updateRoles(viewer, request.threadID, nextThreadType);
       }
       return await recalculateAllPermissions(request.threadID, nextThreadType);
     })();
   }
   const {
     addMembersChangeset,
     recalculatePermissionsChangeset,
   } = await promiseAll(intermediatePromises);
 
   const membershipRows = [];
   const relationshipRows = [];
   if (recalculatePermissionsChangeset && newMemberIDs) {
     const {
       membershipRows: recalculateMembershipRows,
       relationshipRows: recalculateRelationshipRows,
     } = recalculatePermissionsChangeset;
     membershipRows.push(...recalculateMembershipRows);
     const parentRelationshipRows = getParentThreadRelationshipRowsForNewUsers(
       request.threadID,
       recalculateMembershipRows,
       newMemberIDs,
     );
     relationshipRows.push(
       ...recalculateRelationshipRows,
       ...parentRelationshipRows,
     );
   } else if (recalculatePermissionsChangeset) {
     const {
       membershipRows: recalculateMembershipRows,
       relationshipRows: recalculateRelationshipRows,
     } = recalculatePermissionsChangeset;
     membershipRows.push(...recalculateMembershipRows);
     relationshipRows.push(...recalculateRelationshipRows);
   }
   if (addMembersChangeset) {
     const {
       membershipRows: addMembersMembershipRows,
       relationshipRows: addMembersRelationshipRows,
     } = addMembersChangeset;
     relationshipRows.push(...addMembersRelationshipRows);
     setJoinsToUnread(addMembersMembershipRows, viewer.userID, request.threadID);
     membershipRows.push(...addMembersMembershipRows);
   }
 
   const changeset = { membershipRows, relationshipRows };
   const { threadInfos, viewerUpdates } = await commitMembershipChangeset(
     viewer,
     changeset,
     {
       // This forces an update for this thread,
       // regardless of whether any membership rows are changed
       changedThreadIDs:
         Object.keys(sqlUpdate).length > 0
           ? new Set([request.threadID])
           : new Set(),
     },
   );
 
   const time = Date.now();
   const messageDatas = [];
   for (let fieldName in changedFields) {
     const newValue = changedFields[fieldName];
     messageDatas.push({
       type: messageTypes.CHANGE_SETTINGS,
       threadID: request.threadID,
       creatorID: viewer.userID,
       time,
       field: fieldName,
       value: newValue,
     });
   }
   if (newMemberIDs) {
     messageDatas.push({
       type: messageTypes.ADD_MEMBERS,
       threadID: request.threadID,
       creatorID: viewer.userID,
       time,
       addedUserIDs: newMemberIDs,
     });
   }
   const newMessageInfos = await createMessages(viewer, messageDatas);
 
   if (hasMinCodeVersion(viewer.platformDetails, 62)) {
     return { updatesResult: { newUpdates: viewerUpdates }, newMessageInfos };
   }
 
   return {
     threadInfo: threadInfos[request.threadID],
     threadInfos,
     updatesResult: {
       newUpdates: viewerUpdates,
     },
     newMessageInfos,
   };
 }
 
 async function joinThread(
   viewer: Viewer,
   request: ServerThreadJoinRequest,
 ): Promise<ThreadJoinResult> {
   if (!viewer.loggedIn) {
     throw new ServerError('not_logged_in');
   }
 
   const [isMember, hasPermission] = await Promise.all([
     fetchViewerIsMember(viewer, request.threadID),
     checkThreadPermission(
       viewer,
       request.threadID,
       threadPermissions.JOIN_THREAD,
     ),
   ]);
   if (isMember || !hasPermission) {
     throw new ServerError('invalid_parameters');
   }
 
   const { calendarQuery } = request;
   if (calendarQuery) {
     const threadFilterIDs = filteredThreadIDs(calendarQuery.filters);
     if (
       !threadFilterIDs ||
       threadFilterIDs.size !== 1 ||
       threadFilterIDs.values().next().value !== request.threadID
     ) {
       throw new ServerError('invalid_parameters');
     }
   }
 
   const changeset = await changeRole(request.threadID, [viewer.userID], null);
   if (!changeset) {
     throw new ServerError('unknown_error');
   }
   setJoinsToUnread(changeset.membershipRows, viewer.userID, request.threadID);
 
   const membershipResult = await commitMembershipChangeset(viewer, changeset, {
     calendarQuery,
   });
 
   const messageData = {
     type: messageTypes.JOIN_THREAD,
     threadID: request.threadID,
     creatorID: viewer.userID,
     time: Date.now(),
   };
   await createMessages(viewer, [messageData]);
 
   const threadSelectionCriteria = {
     threadCursors: { [request.threadID]: false },
   };
   const [fetchMessagesResult, fetchEntriesResult] = await Promise.all([
     fetchMessageInfos(viewer, threadSelectionCriteria, defaultNumberPerThread),
     calendarQuery ? fetchEntryInfos(viewer, [calendarQuery]) : undefined,
   ]);
 
   const rawEntryInfos = fetchEntriesResult && fetchEntriesResult.rawEntryInfos;
   const response: ThreadJoinResult = {
     rawMessageInfos: fetchMessagesResult.rawMessageInfos,
     truncationStatuses: fetchMessagesResult.truncationStatuses,
     userInfos: membershipResult.userInfos,
     updatesResult: {
       newUpdates: membershipResult.viewerUpdates,
     },
   };
   if (!hasMinCodeVersion(viewer.platformDetails, 62)) {
     response.threadInfos = membershipResult.threadInfos;
   }
   if (rawEntryInfos) {
     response.rawEntryInfos = rawEntryInfos;
   }
   return response;
 }
 
 async function updateThreadMembers(viewer: Viewer) {
   const { threadInfos } = await fetchThreadInfos(
     viewer,
     SQL`t.parent_thread_id IS NOT NULL `,
   );
 
   const updateDatas = [];
   const time = Date.now();
   for (const threadID in threadInfos) {
     updateDatas.push({
       type: updateTypes.UPDATE_THREAD,
       userID: viewer.id,
       time,
       threadID: threadID,
       targetSession: viewer.session,
     });
   }
 
   await createUpdates(updateDatas);
 }
 
 export {
   updateRole,
   removeMembers,
   leaveThread,
   updateThread,
   joinThread,
   updateThreadMembers,
 };