diff --git a/keyserver/src/creators/thread-creator.js b/keyserver/src/creators/thread-creator.js
--- a/keyserver/src/creators/thread-creator.js
+++ b/keyserver/src/creators/thread-creator.js
@@ -79,14 +79,12 @@
     throw new ServerError('not_logged_in');
   }
 
-  const forceAddMembers = options?.forceAddMembers ?? false;
   const updatesForCurrentSession =
     options?.updatesForCurrentSession ?? 'return';
   const silentlyFailMembers = options?.silentlyFailMembers ?? false;
 
   const threadType = request.type;
-  const shouldCreateRelationships =
-    forceAddMembers || threadType === threadTypes.PERSONAL;
+  const shouldCreateRelationships = options?.forceAddMembers ?? false;
   let parentThreadID = request.parentThreadID ? request.parentThreadID : null;
   const initialMemberIDsFromRequest =
     request.initialMemberIDs && request.initialMemberIDs.length > 0
diff --git a/keyserver/src/responders/thread-responders.js b/keyserver/src/responders/thread-responders.js
--- a/keyserver/src/responders/thread-responders.js
+++ b/keyserver/src/responders/thread-responders.js
@@ -155,6 +155,7 @@
 
   return await createThread(viewer, request, {
     silentlyFailMembers: request.type === threadTypes.SIDEBAR,
+    forceAddMembers: true,
   });
 }
 
diff --git a/lib/selectors/user-selectors.js b/lib/selectors/user-selectors.js
--- a/lib/selectors/user-selectors.js
+++ b/lib/selectors/user-selectors.js
@@ -113,31 +113,33 @@
   baseRelativeMemberInfoSelectorForMembersOfThread,
 );
 
+function filterPotentialMembers(
+  userInfos: UserInfos,
+  currentUserID: ?string,
+): { [id: string]: AccountUserInfo } {
+  const availableUsers: { [id: string]: AccountUserInfo } = {};
+
+  for (const id in userInfos) {
+    const { username, relationshipStatus } = userInfos[id];
+    if (id === currentUserID || !username) {
+      continue;
+    }
+    if (
+      relationshipStatus !== userRelationshipStatus.BLOCKED_VIEWER &&
+      relationshipStatus !== userRelationshipStatus.BOTH_BLOCKED
+    ) {
+      availableUsers[id] = { id, username, relationshipStatus };
+    }
+  }
+  return availableUsers;
+}
+
 const userInfoSelectorForPotentialMembers: (
   state: BaseAppState<*>,
 ) => { [id: string]: AccountUserInfo } = createSelector(
   (state: BaseAppState<*>) => state.userStore.userInfos,
   (state: BaseAppState<*>) => state.currentUserInfo && state.currentUserInfo.id,
-  (
-    userInfos: UserInfos,
-    currentUserID: ?string,
-  ): { [id: string]: AccountUserInfo } => {
-    const availableUsers: { [id: string]: AccountUserInfo } = {};
-
-    for (const id in userInfos) {
-      const { username, relationshipStatus } = userInfos[id];
-      if (id === currentUserID || !username) {
-        continue;
-      }
-      if (
-        relationshipStatus !== userRelationshipStatus.BLOCKED_VIEWER &&
-        relationshipStatus !== userRelationshipStatus.BOTH_BLOCKED
-      ) {
-        availableUsers[id] = { id, username, relationshipStatus };
-      }
-    }
-    return availableUsers;
-  },
+  filterPotentialMembers,
 );
 
 function searchIndexFromUserInfos(userInfos: {
@@ -215,4 +217,5 @@
   isLoggedIn,
   userStoreSearchIndex,
   usersWithPersonalThreadSelector,
+  filterPotentialMembers,
 };
diff --git a/web/chat/chat-message-list-container.react.js b/web/chat/chat-message-list-container.react.js
--- a/web/chat/chat-message-list-container.react.js
+++ b/web/chat/chat-message-list-container.react.js
@@ -2,7 +2,6 @@
 
 import classNames from 'classnames';
 import invariant from 'invariant';
-import _isEqual from 'lodash/fp/isEqual';
 import * as React from 'react';
 import { useDrop } from 'react-dnd';
 import { NativeTypes } from 'react-dnd-html5-backend';
@@ -17,7 +16,6 @@
   threadIsPending,
 } from 'lib/shared/thread-utils';
 import { threadTypes } from 'lib/types/thread-types';
-import type { AccountUserInfo } from 'lib/types/user-types';
 
 import { InputStateContext } from '../input/input-state';
 import { updateNavInfoActionType } from '../redux/action-types';
@@ -37,12 +35,32 @@
   const isChatCreation =
     useSelector(state => state.navInfo.chatMode) === 'create';
 
-  const selectedUserIDs = useSelector(state => state.navInfo.selectedUserList);
+  const selectedUserIDs = useSelector(
+    state => state.navInfo.selectedUserList ?? [],
+  );
   const otherUserInfos = useSelector(userInfoSelectorForPotentialMembers);
-  const userInfoInputArray: $ReadOnlyArray<AccountUserInfo> = React.useMemo(
-    () => selectedUserIDs?.map(id => otherUserInfos[id]).filter(Boolean) ?? [],
-    [otherUserInfos, selectedUserIDs],
+  const [userInfoInputArray, setUserInfoInputArray] = React.useState(() =>
+    selectedUserIDs.map(id => otherUserInfos[id]).filter(Boolean),
   );
+
+  React.useEffect(() => {
+    if (!isChatCreation) {
+      setUserInfoInputArray([]);
+    }
+  }, [isChatCreation]);
+
+  const dispatch = useDispatch();
+  React.useEffect(() => {
+    if (isChatCreation) {
+      dispatch({
+        type: updateNavInfoActionType,
+        payload: {
+          selectedUserList: userInfoInputArray.map(user => user.id),
+        },
+      });
+    }
+  }, [dispatch, isChatCreation, userInfoInputArray]);
+
   const viewerID = useSelector(state => state.currentUserInfo?.id);
   invariant(viewerID, 'should be set');
 
@@ -105,36 +123,6 @@
   ]);
   invariant(threadInfo, 'ThreadInfo should be set');
 
-  const dispatch = useDispatch();
-
-  // The effect removes members from list in navInfo
-  // if some of the user IDs don't exist in redux store
-  React.useEffect(() => {
-    if (!isChatCreation) {
-      return;
-    }
-    const existingSelectedUsersSet = new Set(
-      userInfoInputArray.map(userInfo => userInfo.id),
-    );
-    if (
-      selectedUserIDs?.length !== existingSelectedUsersSet.size ||
-      !_isEqual(new Set(selectedUserIDs), existingSelectedUsersSet)
-    ) {
-      dispatch({
-        type: updateNavInfoActionType,
-        payload: {
-          selectedUserList: Array.from(existingSelectedUsersSet),
-        },
-      });
-    }
-  }, [
-    dispatch,
-    isChatCreation,
-    otherUserInfos,
-    selectedUserIDs,
-    userInfoInputArray,
-  ]);
-
   React.useEffect(() => {
     if (isChatCreation && activeChatThreadID !== threadInfo?.id) {
       let payload = {
@@ -226,6 +214,7 @@
     const chatUserSelection = (
       <ChatThreadComposer
         userInfoInputArray={userInfoInputArray}
+        setUserInfoInputArray={setUserInfoInputArray}
         otherUserInfos={otherUserInfos}
         threadID={threadInfo.id}
         inputState={inputState}
diff --git a/web/chat/chat-thread-composer.react.js b/web/chat/chat-thread-composer.react.js
--- a/web/chat/chat-thread-composer.react.js
+++ b/web/chat/chat-thread-composer.react.js
@@ -3,10 +3,13 @@
 import * as React from 'react';
 import { useDispatch } from 'react-redux';
 
-import { userSearchIndexForPotentialMembers } from 'lib/selectors/user-selectors';
+import { searchUsers } from 'lib/actions/user-actions';
+import { filterPotentialMembers } from 'lib/selectors/user-selectors';
+import SearchIndex from 'lib/shared/search-index';
 import { getPotentialMemberItems } from 'lib/shared/search-utils';
 import { threadIsPending } from 'lib/shared/thread-utils';
 import type { AccountUserInfo, UserListItem } from 'lib/types/user-types';
+import { useServerCall } from 'lib/utils/action-utils';
 
 import Button from '../components/button.react';
 import Label from '../components/label.react';
@@ -19,6 +22,9 @@
 
 type Props = {
   +userInfoInputArray: $ReadOnlyArray<AccountUserInfo>,
+  +setUserInfoInputArray: (
+    ($ReadOnlyArray<AccountUserInfo>) => $ReadOnlyArray<AccountUserInfo>,
+  ) => void,
   +otherUserInfos: { [id: string]: AccountUserInfo },
   +threadID: string,
   +inputState: InputState,
@@ -29,12 +35,61 @@
   | 'keep-active-thread';
 
 function ChatThreadComposer(props: Props): React.Node {
-  const { userInfoInputArray, otherUserInfos, threadID, inputState } = props;
+  const {
+    userInfoInputArray,
+    setUserInfoInputArray,
+    otherUserInfos,
+    threadID,
+    inputState,
+  } = props;
 
   const [usernameInputText, setUsernameInputText] = React.useState('');
 
-  const dispatch = useDispatch();
-  const userSearchIndex = useSelector(userSearchIndexForPotentialMembers);
+  const userInfos = useSelector(state => state.userStore.userInfos);
+  const viewerID = useSelector(state => state.currentUserInfo?.id);
+  const [serverSearchUserInfos, setServerSearchUserInfos] = React.useState<{
+    [id: string]: AccountUserInfo,
+  }>({});
+  const callSearchUsers = useServerCall(searchUsers);
+  React.useEffect(() => {
+    (async () => {
+      if (usernameInputText.length === 0) {
+        setServerSearchUserInfos({});
+      } else {
+        const { userInfos: serverUserInfos } = await callSearchUsers(
+          usernameInputText,
+        );
+        const result = {};
+        for (const user of serverUserInfos) {
+          if (!(user.id in userInfos)) {
+            result[user.id] = user;
+          }
+        }
+        const potentialMembers = filterPotentialMembers(result, viewerID);
+        setServerSearchUserInfos(potentialMembers);
+      }
+    })();
+  }, [userInfos, callSearchUsers, usernameInputText, viewerID]);
+
+  const {
+    mergedUserInfos,
+    userSearchIndex,
+  }: {
+    mergedUserInfos: { [id: string]: AccountUserInfo },
+    userSearchIndex: SearchIndex,
+  } = React.useMemo(() => {
+    const bothUserInfos = { ...serverSearchUserInfos, ...otherUserInfos };
+
+    const searchIndex = new SearchIndex();
+    for (const id in bothUserInfos) {
+      searchIndex.addEntry(id, bothUserInfos[id].username);
+    }
+
+    return {
+      mergedUserInfos: bothUserInfos,
+      userSearchIndex: searchIndex,
+    };
+  }, [serverSearchUserInfos, otherUserInfos]);
 
   const userInfoInputIDs = React.useMemo(
     () => userInfoInputArray.map(userInfo => userInfo.id),
@@ -45,41 +100,31 @@
     () =>
       getPotentialMemberItems(
         usernameInputText,
-        otherUserInfos,
+        mergedUserInfos,
         userSearchIndex,
         userInfoInputIDs,
       ),
-    [usernameInputText, otherUserInfos, userSearchIndex, userInfoInputIDs],
+    [usernameInputText, mergedUserInfos, userSearchIndex, userInfoInputIDs],
   );
 
   const onSelectUserFromSearch = React.useCallback(
-    (id: string) => {
-      const selectedUserIDs = userInfoInputArray.map(user => user.id);
-      dispatch({
-        type: updateNavInfoActionType,
-        payload: {
-          selectedUserList: [...selectedUserIDs, id],
-        },
-      });
+    (id: string, username: string) => {
+      setUserInfoInputArray(previousUserInfoInputArray => [
+        ...previousUserInfoInputArray,
+        { id, username },
+      ]);
       setUsernameInputText('');
     },
-    [dispatch, userInfoInputArray],
+    [setUserInfoInputArray],
   );
 
   const onRemoveUserFromSelected = React.useCallback(
     (id: string) => {
-      const selectedUserIDs = userInfoInputArray.map(user => user.id);
-      if (!selectedUserIDs.includes(id)) {
-        return;
-      }
-      dispatch({
-        type: updateNavInfoActionType,
-        payload: {
-          selectedUserList: selectedUserIDs.filter(userID => userID !== id),
-        },
-      });
+      setUserInfoInputArray(previousUserInfoInputArray =>
+        previousUserInfoInputArray.filter(user => user.id !== id),
+      );
     },
-    [dispatch, userInfoInputArray],
+    [setUserInfoInputArray],
   );
 
   const userSearchResultList = React.useMemo(() => {
@@ -96,7 +141,12 @@
           <li key={userSearchResult.id} className={css.searchResultsItem}>
             <Button
               variant="text"
-              onClick={() => onSelectUserFromSearch(userSearchResult.id)}
+              onClick={() =>
+                onSelectUserFromSearch(
+                  userSearchResult.id,
+                  userSearchResult.username,
+                )
+              }
               className={css.searchResultsButton}
             >
               <div className={css.userName}>{userSearchResult.username}</div>
@@ -113,6 +163,7 @@
     usernameInputText,
   ]);
 
+  const dispatch = useDispatch();
   const hideSearch = React.useCallback(
     (threadBehavior: ActiveThreadBehavior = 'keep-active-thread') => {
       dispatch({