diff --git a/lib/permissions/add-users-permissions.js b/lib/permissions/add-users-permissions.js
new file mode 100644
--- /dev/null
+++ b/lib/permissions/add-users-permissions.js
@@ -0,0 +1,41 @@
+// @flow
+
+import { primaryInviteLinksSelector } from '../selectors/invite-links-selectors.js';
+import { useThreadHasPermission } from '../shared/thread-utils.js';
+import type { InviteLink } from '../types/link-types.js';
+import type { ThreadInfo } from '../types/minimally-encoded-thread-permissions-types.js';
+import { threadPermissions } from '../types/thread-permission-types.js';
+import { threadTypeIsCommunityRoot } from '../types/thread-types-enum.js';
+import { useSelector } from '../utils/redux-utils.js';
+
+type AddUsersPermissions = {
+  +inviteLink: InviteLink,
+  +canManageLinks: boolean,
+  +canAddMembers: boolean,
+  +isCommunityRoot: boolean,
+};
+
+function useAddUsersPermissions(threadInfo: ThreadInfo): AddUsersPermissions {
+  const inviteLink = useSelector(primaryInviteLinksSelector)[threadInfo.id];
+  const canManageLinks = useThreadHasPermission(
+    threadInfo,
+    threadPermissions.MANAGE_INVITE_LINKS,
+  );
+
+  const isCommunityRoot = threadTypeIsCommunityRoot(threadInfo.type);
+
+  const canAddMembersViaInviteLink =
+    isCommunityRoot && (!!inviteLink || canManageLinks);
+
+  const hasAddMembersPermission = useThreadHasPermission(
+    threadInfo,
+    threadPermissions.ADD_MEMBERS,
+  );
+  const canAddMembersManually = hasAddMembersPermission && !isCommunityRoot;
+
+  const canAddMembers = canAddMembersManually || canAddMembersViaInviteLink;
+
+  return { inviteLink, canManageLinks, canAddMembers, isCommunityRoot };
+}
+
+export { useAddUsersPermissions };
diff --git a/web/modals/threads/members/members-modal.react.js b/web/modals/threads/members/members-modal.react.js
--- a/web/modals/threads/members/members-modal.react.js
+++ b/web/modals/threads/members/members-modal.react.js
@@ -3,16 +3,11 @@
 import * as React from 'react';
 
 import { useModalContext } from 'lib/components/modal-provider.react.js';
-import { primaryInviteLinksSelector } from 'lib/selectors/invite-links-selectors.js';
+import { useAddUsersPermissions } from 'lib/permissions/add-users-permissions.js';
 import { useUserSearchIndex } from 'lib/selectors/nav-selectors.js';
 import { threadInfoSelector } from 'lib/selectors/thread-selectors.js';
-import {
-  roleIsAdminRole,
-  useThreadHasPermission,
-} from 'lib/shared/thread-utils.js';
+import { roleIsAdminRole } from 'lib/shared/thread-utils.js';
 import type { RelativeMemberInfo } from 'lib/types/minimally-encoded-thread-permissions-types.js';
-import { threadPermissions } from 'lib/types/thread-permission-types.js';
-import { threadTypeIsCommunityRoot } from 'lib/types/thread-types-enum.js';
 import { useRolesFromCommunityThreadInfo } from 'lib/utils/role-utils.js';
 
 import { AddMembersModal } from './add-members-modal.react.js';
@@ -121,13 +116,8 @@
 
   const threadInfo = useSelector(state => threadInfoSelector(state)[threadID]);
 
-  const inviteLink = useSelector(primaryInviteLinksSelector)[threadID];
-  const canManageLinks = useThreadHasPermission(
-    threadInfo,
-    threadPermissions.MANAGE_INVITE_LINKS,
-  );
-
-  const isCommunityRoot = threadTypeIsCommunityRoot(threadInfo.type);
+  const { inviteLink, canManageLinks, canAddMembers, isCommunityRoot } =
+    useAddUsersPermissions(threadInfo);
 
   const onClickAddMembers = React.useCallback(() => {
     if (!isCommunityRoot) {
@@ -146,17 +136,6 @@
     threadID,
   ]);
 
-  const canAddMembersViaInviteLink =
-    isCommunityRoot && (inviteLink || canManageLinks);
-
-  const hasAddMembersPermission = useThreadHasPermission(
-    threadInfo,
-    threadPermissions.ADD_MEMBERS,
-  );
-  const canAddMembersManually = hasAddMembersPermission && !isCommunityRoot;
-
-  const canAddMembers = canAddMembersManually || canAddMembersViaInviteLink;
-
   const addMembersButton = React.useMemo(() => {
     if (!canAddMembers) {
       return null;