diff --git a/lib/shared/search-utils.js b/lib/shared/search-utils.js
--- a/lib/shared/search-utils.js
+++ b/lib/shared/search-utils.js
@@ -32,6 +32,9 @@
       ? inputParentThreadInfo
       : null;
 
+  const containingThreadInfo =
+    threadType === threadTypes.SIDEBAR ? parentThreadInfo : communityThreadInfo;
+
   let results = [];
   const appendUserInfo = (userInfo: AccountUserInfo) => {
     const { id } = userInfo;
@@ -51,6 +54,7 @@
     results.push({
       ...userInfo,
       isMemberOfParentThread: userIsMember(parentThreadInfo, id),
+      isMemberOfContainingThread: userIsMember(containingThreadInfo, id),
     });
   };
   if (text === '') {
@@ -64,75 +68,87 @@
     }
   }
 
+  const blockedRelationshipsStatuses = new Set([
+    userRelationshipStatus.BLOCKED_BY_VIEWER,
+    userRelationshipStatus.BLOCKED_VIEWER,
+    userRelationshipStatus.BOTH_BLOCKED,
+  ]);
+
   if (text === '') {
     results = results.filter(userInfo =>
-      parentThreadInfo
-        ? userInfo.isMemberOfParentThread &&
-          userInfo.relationshipStatus !==
-            userRelationshipStatus.BLOCKED_BY_VIEWER
+      containingThreadInfo
+        ? userInfo.isMemberOfContainingThread &&
+          !blockedRelationshipsStatuses.has(userInfo.relationshipStatus)
         : userInfo.relationshipStatus === userRelationshipStatus.FRIEND,
     );
   }
 
   const nonFriends = [];
   const blockedUsers = [];
-  const friendsAndParentMembers = [];
+  const friendsAndContainingThreadMembers = [];
 
   for (const userResult of results) {
     const relationshipStatus = userResult.relationshipStatus;
     if (
-      userResult.isMemberOfParentThread &&
-      relationshipStatus !== userRelationshipStatus.BLOCKED_BY_VIEWER
+      userResult.isMemberOfContainingThread &&
+      !blockedRelationshipsStatuses.has(relationshipStatus)
     ) {
-      friendsAndParentMembers.unshift(userResult);
+      friendsAndContainingThreadMembers.unshift(userResult);
     } else if (relationshipStatus === userRelationshipStatus.FRIEND) {
-      friendsAndParentMembers.push(userResult);
-    } else if (
-      relationshipStatus === userRelationshipStatus.BLOCKED_BY_VIEWER
-    ) {
+      friendsAndContainingThreadMembers.push(userResult);
+    } else if (blockedRelationshipsStatuses.has(relationshipStatus)) {
       blockedUsers.push(userResult);
     } else {
       nonFriends.push(userResult);
     }
   }
 
-  const sortedResults = friendsAndParentMembers
+  const sortedResults = friendsAndContainingThreadMembers
     .concat(nonFriends)
     .concat(blockedUsers);
 
   return sortedResults.map(
-    ({ isMemberOfParentThread, relationshipStatus, ...result }) => {
-      if (
-        isMemberOfParentThread &&
-        relationshipStatus !== userRelationshipStatus.BLOCKED_BY_VIEWER
+    ({
+      isMemberOfContainingThread,
+      isMemberOfParentThread,
+      relationshipStatus,
+      ...result
+    }) => {
+      let notice, alertText, alertTitle;
+      const username = result.username;
+      if (blockedRelationshipsStatuses.has(relationshipStatus)) {
+        notice = 'user is blocked';
+        alertTitle = 'User is blocked';
+        alertText =
+          `Before you add ${username} to this chat, ` +
+          'you’ll need to unblock them. You can do this from the Block List ' +
+          'in the Profile tab.';
+      } else if (!isMemberOfContainingThread && containingThreadInfo) {
+        if (threadType !== threadTypes.SIDEBAR) {
+          notice = 'not in community';
+          alertTitle = 'Not in community';
+          alertText = 'You can only add members of the community to this chat';
+        } else {
+          notice = 'not in parent chat';
+          alertTitle = 'Not in parent chat';
+          alertText = 'You can only add members of the parent chat to a thread';
+        }
+      } else if (
+        !containingThreadInfo &&
+        relationshipStatus === userRelationshipStatus.FRIEND
       ) {
         return { ...result };
-      }
-      let notice, alertText, alertTitle;
-      const userText = result.username;
-      if (!isMemberOfParentThread && threadType === threadTypes.SIDEBAR) {
-        notice = 'not in parent chat';
-        alertTitle = 'Not in parent chat';
-        alertText = 'You can only add members of the parent chat to a thread';
       } else if (
-        relationshipStatus === userRelationshipStatus.BLOCKED_BY_VIEWER
+        !containingThreadInfo &&
+        relationshipStatus !== userRelationshipStatus.FRIEND
       ) {
-        notice = 'you’ve blocked this user';
-        alertTitle = 'Not a friend';
-        alertText =
-          `Before you add ${userText} to this chat, ` +
-          'you’ll need to unblock them and send a friend request. ' +
-          'You can do this from the Block List and Friend List ' +
-          'in the Profile tab.';
-      } else if (relationshipStatus !== userRelationshipStatus.FRIEND) {
         notice = notFriendNotice;
+        alertTitle = 'not friend';
         alertTitle = 'Not a friend';
         alertText =
-          `Before you add ${userText} to this chat, ` +
+          `Before you add ${username} to this chat, ` +
           'you’ll need to send them a friend request. ' +
           'You can do this from the Friend List in the Profile tab.';
-      } else if (parentThreadInfo) {
-        notice = 'not in parent chat';
       }
       return { ...result, notice, alertText, alertTitle };
     },