Cannot edit XWiki.XWikiAllGroup as there are too many users in it.

The user XWiki.Templates was added on beta and then imported into production, but in doing so it did not get associated with any groups.

The issue is that we can not simply add it to the group because the group page for XWikiAllGroup will not load (due to over 30000 users trying to be listed).

1) Can we just delete and recreate the user on production to get it into the group as a quick fix (or will that cause issue with things that refer to it as an owner/author) ?
2) We need to fix the group page so that we can add/remove users even with groups as large as the XWikiAllGroup group.