diff --git a/keyserver/src/responders/message-responders.js b/keyserver/src/responders/message-responders.js
index 20777a773..2e4ba4420 100644
--- a/keyserver/src/responders/message-responders.js
+++ b/keyserver/src/responders/message-responders.js
@@ -1,361 +1,383 @@
 // @flow
 
 import invariant from 'invariant';
 import t from 'tcomb';
 
 import { onlyOneEmojiRegex } from 'lib/shared/emojis.js';
 import {
   createMediaMessageData,
   trimMessage,
 } from 'lib/shared/message-utils.js';
 import { relationshipBlockedInEitherDirection } from 'lib/shared/relationship-utils.js';
 import type { Media } from 'lib/types/media-types.js';
 import {
   messageTypes,
   type SendTextMessageRequest,
   type SendMultimediaMessageRequest,
   type SendReactionMessageRequest,
   type SendEditMessageRequest,
   type FetchMessageInfosResponse,
   type FetchMessageInfosRequest,
   defaultNumberPerThread,
   type SendMessageResponse,
   type SendEditMessageResponse,
 } from 'lib/types/message-types.js';
 import type { EditMessageData } from 'lib/types/messages/edit.js';
 import type { ReactionMessageData } from 'lib/types/messages/reaction.js';
 import type { TextMessageData } from 'lib/types/messages/text.js';
 import { threadPermissions } from 'lib/types/thread-types.js';
 import { ServerError } from 'lib/utils/errors.js';
+import { values } from 'lib/utils/objects.js';
 import {
   tRegex,
   tShape,
   tMediaMessageMedia,
 } from 'lib/utils/validation-utils.js';
 
 import createMessages from '../creators/message-creator.js';
 import { SQL } from '../database/database.js';
 import {
   fetchMessageInfos,
   fetchMessageInfoForLocalID,
   fetchMessageInfoByID,
   fetchThreadMessagesCount,
 } from '../fetchers/message-fetchers.js';
 import { fetchServerThreadInfos } from '../fetchers/thread-fetchers.js';
 import { checkThreadPermission } from '../fetchers/thread-permission-fetchers.js';
 import {
   fetchMedia,
   fetchMediaFromMediaMessageContent,
 } from '../fetchers/upload-fetchers.js';
 import { fetchKnownUserInfos } from '../fetchers/user-fetchers.js';
 import type { Viewer } from '../session/viewer.js';
 import {
   assignMedia,
   assignMessageContainerToMedia,
 } from '../updaters/upload-updaters.js';
 import { validateInput } from '../utils/validation-utils.js';
 
 const sendTextMessageRequestInputValidator = tShape({
   threadID: t.String,
   localID: t.maybe(t.String),
   text: t.String,
   sidebarCreation: t.maybe(t.Boolean),
 });
 async function textMessageCreationResponder(
   viewer: Viewer,
   input: any,
 ): Promise<SendMessageResponse> {
   const request: SendTextMessageRequest = input;
   await validateInput(viewer, sendTextMessageRequestInputValidator, request);
 
   const { threadID, localID, text: rawText, sidebarCreation } = request;
   const text = trimMessage(rawText);
   if (!text) {
     throw new ServerError('invalid_parameters');
   }
 
   const hasPermission = await checkThreadPermission(
     viewer,
     threadID,
     threadPermissions.VOICED,
   );
   if (!hasPermission) {
     throw new ServerError('invalid_parameters');
   }
 
   let messageData: TextMessageData = {
     type: messageTypes.TEXT,
     threadID,
     creatorID: viewer.id,
     time: Date.now(),
     text,
   };
   if (localID) {
     messageData = { ...messageData, localID };
   }
   if (sidebarCreation) {
     const numMessages = await fetchThreadMessagesCount(threadID);
     if (numMessages === 2) {
       // sidebarCreation is set below to prevent double notifs from a sidebar
       // creation. We expect precisely two messages to appear before a
       // sidebarCreation: a SIDEBAR_SOURCE and a CREATE_SIDEBAR. If two users
       // attempt to create a sidebar at the same time, then both clients will
       // attempt to set sidebarCreation here, but we only want to suppress
       // notifs for the client that won the race.
       messageData = { ...messageData, sidebarCreation };
     }
   }
   const rawMessageInfos = await createMessages(viewer, [messageData]);
 
   return { newMessageInfo: rawMessageInfos[0] };
 }
 
 const fetchMessageInfosRequestInputValidator = tShape({
   cursors: t.dict(t.String, t.maybe(t.String)),
   numberPerThread: t.maybe(t.Number),
 });
 async function messageFetchResponder(
   viewer: Viewer,
   input: any,
 ): Promise<FetchMessageInfosResponse> {
   const request: FetchMessageInfosRequest = input;
   await validateInput(viewer, fetchMessageInfosRequestInputValidator, request);
   const response = await fetchMessageInfos(
     viewer,
     { threadCursors: request.cursors },
     request.numberPerThread ? request.numberPerThread : defaultNumberPerThread,
   );
   return { ...response, userInfos: {} };
 }
 
 const sendMultimediaMessageRequestInputValidator = t.union([
   tShape({
     threadID: t.String,
     localID: t.String,
     sidebarCreation: t.maybe(t.Boolean),
     mediaIDs: t.list(t.String),
   }),
   tShape({
     threadID: t.String,
     localID: t.String,
     sidebarCreation: t.maybe(t.Boolean),
     mediaMessageContents: t.list(tMediaMessageMedia),
   }),
 ]);
 async function multimediaMessageCreationResponder(
   viewer: Viewer,
   input: any,
 ): Promise<SendMessageResponse> {
   const request: SendMultimediaMessageRequest = input;
   await validateInput(
     viewer,
     sendMultimediaMessageRequestInputValidator,
     request,
   );
 
   if (
     (request.mediaIDs && request.mediaIDs.length === 0) ||
     (request.mediaMessageContents && request.mediaMessageContents.length === 0)
   ) {
     throw new ServerError('invalid_parameters');
   }
 
   const { threadID, localID, sidebarCreation } = request;
   const hasPermission = await checkThreadPermission(
     viewer,
     threadID,
     threadPermissions.VOICED,
   );
   if (!hasPermission) {
     throw new ServerError('invalid_parameters');
   }
 
   const existingMessageInfoPromise = fetchMessageInfoForLocalID(
     viewer,
     localID,
   );
   const mediaPromise: Promise<$ReadOnlyArray<Media>> = request.mediaIDs
     ? fetchMedia(viewer, request.mediaIDs)
     : fetchMediaFromMediaMessageContent(viewer, request.mediaMessageContents);
 
   const [existingMessageInfo, media] = await Promise.all([
     existingMessageInfoPromise,
     mediaPromise,
   ]);
 
   if (media.length === 0 && !existingMessageInfo) {
     throw new ServerError('invalid_parameters');
   }
 
   const messageData = createMediaMessageData({
     localID,
     threadID,
     creatorID: viewer.id,
     media,
     sidebarCreation,
   });
   const [newMessageInfo] = await createMessages(viewer, [messageData]);
   const { id } = newMessageInfo;
   invariant(
     id !== null && id !== undefined,
     'serverID should be set in createMessages result',
   );
 
   if (request.mediaIDs) {
     await assignMedia(viewer, request.mediaIDs, id, threadID);
   } else {
     await assignMessageContainerToMedia(
       viewer,
       request.mediaMessageContents,
       id,
       threadID,
     );
   }
 
   return { newMessageInfo };
 }
 
 const sendReactionMessageRequestInputValidator = tShape({
   threadID: t.String,
   localID: t.maybe(t.String),
   targetMessageID: t.String,
   reaction: tRegex(onlyOneEmojiRegex),
   action: t.enums.of(['add_reaction', 'remove_reaction']),
 });
 async function reactionMessageCreationResponder(
   viewer: Viewer,
   input: any,
 ): Promise<SendMessageResponse> {
   const request: SendReactionMessageRequest = input;
   await validateInput(viewer, sendReactionMessageRequestInputValidator, input);
 
   const { threadID, localID, targetMessageID, reaction, action } = request;
 
   if (!targetMessageID || !reaction) {
     throw new ServerError('invalid_parameters');
   }
 
   const targetMessageInfo = await fetchMessageInfoByID(viewer, targetMessageID);
 
   if (!targetMessageInfo || !targetMessageInfo.id) {
     throw new ServerError('invalid_parameters');
   }
 
   const [serverThreadInfos, hasPermission, targetMessageUserInfos] =
     await Promise.all([
       fetchServerThreadInfos(SQL`t.id = ${threadID}`),
       checkThreadPermission(
         viewer,
         threadID,
         threadPermissions.REACT_TO_MESSAGE,
       ),
       fetchKnownUserInfos(viewer, [targetMessageInfo.creatorID]),
     ]);
 
   const targetMessageThreadInfo = serverThreadInfos.threadInfos[threadID];
   if (targetMessageThreadInfo.sourceMessageID === targetMessageID) {
     throw new ServerError('invalid_parameters');
   }
 
   const targetMessageCreator =
     targetMessageUserInfos[targetMessageInfo.creatorID];
 
   const targetMessageCreatorRelationship =
     targetMessageCreator?.relationshipStatus;
 
   const creatorRelationshipHasBlock =
     targetMessageCreatorRelationship &&
     relationshipBlockedInEitherDirection(targetMessageCreatorRelationship);
 
   if (!hasPermission || creatorRelationshipHasBlock) {
     throw new ServerError('invalid_parameters');
   }
 
   let messageData: ReactionMessageData = {
     type: messageTypes.REACTION,
     threadID,
     creatorID: viewer.id,
     time: Date.now(),
     targetMessageID,
     reaction,
     action,
   };
   if (localID) {
     messageData = { ...messageData, localID };
   }
 
   const rawMessageInfos = await createMessages(viewer, [messageData]);
 
   return { newMessageInfo: rawMessageInfos[0] };
 }
 
 const editMessageRequestInputValidator = tShape({
   targetMessageID: t.String,
   text: t.String,
 });
 async function editMessageCreationResponder(
   viewer: Viewer,
   input: any,
 ): Promise<SendEditMessageResponse> {
   const request: SendEditMessageRequest = input;
   await validateInput(viewer, editMessageRequestInputValidator, input);
 
   const { targetMessageID, text: rawText } = request;
   const text = trimMessage(rawText);
   if (!targetMessageID || !text) {
     throw new ServerError('invalid_parameters');
   }
 
   const targetMessageInfo = await fetchMessageInfoByID(viewer, targetMessageID);
   if (!targetMessageInfo || !targetMessageInfo.id) {
     throw new ServerError('invalid_parameters');
   }
 
   if (targetMessageInfo.type !== messageTypes.TEXT) {
     throw new ServerError('invalid_parameters');
   }
 
   const { threadID } = targetMessageInfo;
-  const [serverThreadInfos, hasPermission] = await Promise.all([
-    fetchServerThreadInfos(SQL`t.id = ${threadID}`),
-    checkThreadPermission(viewer, threadID, threadPermissions.EDIT_MESSAGE),
-  ]);
+
+  const [serverThreadInfos, hasPermission, rawSidebarThreadInfos] =
+    await Promise.all([
+      fetchServerThreadInfos(SQL`t.id = ${threadID}`),
+      checkThreadPermission(viewer, threadID, threadPermissions.EDIT_MESSAGE),
+      fetchServerThreadInfos(
+        SQL`t.parent_thread_id = ${threadID} AND t.source_message = ${targetMessageID}`,
+      ),
+    ]);
 
   const targetMessageThreadInfo = serverThreadInfos.threadInfos[threadID];
   if (targetMessageThreadInfo.sourceMessageID === targetMessageID) {
     // We are editing first message of the sidebar
     // If client wants to do that it sends id of the sourceMessage instead
     throw new ServerError('invalid_parameters');
   }
 
   if (!hasPermission) {
     throw new ServerError('invalid_parameters');
   }
 
   if (targetMessageInfo.creatorID !== viewer.id) {
     throw new ServerError('invalid_parameters');
   }
 
+  const time = Date.now();
   const messagesData = [];
-  const messageData: EditMessageData = {
+  let messageData: EditMessageData = {
     type: messageTypes.EDIT_MESSAGE,
     threadID,
     creatorID: viewer.id,
-    time: Date.now(),
+    time,
     targetMessageID,
     text,
   };
   messagesData.push(messageData);
 
+  const sidebarThreadValues = values(rawSidebarThreadInfos.threadInfos);
+  for (const sidebarThreadValue of sidebarThreadValues) {
+    if (sidebarThreadValue && sidebarThreadValue.id) {
+      messageData = {
+        type: messageTypes.EDIT_MESSAGE,
+        threadID: sidebarThreadValue.id,
+        creatorID: viewer.id,
+        time,
+        targetMessageID,
+        text: text,
+      };
+      messagesData.push(messageData);
+    }
+  }
+
   const newMessageInfos = await createMessages(viewer, messagesData);
 
   return { newMessageInfos };
 }
 
 export {
   textMessageCreationResponder,
   messageFetchResponder,
   multimediaMessageCreationResponder,
   reactionMessageCreationResponder,
   editMessageCreationResponder,
 };