Ok trying to keep it simple but it does get complex..

Scenario: You make a member group to be the moderating team of a forum, but you set members of it by putting it in their secondary group instead of as their primary group.

If you select that member group to be hidden, then clicking the member groups name on the "Forum led by:" link, you'll get an error. If it's not hidden, then clicking on it should list members who are associated with that member group status.

Also a forum moderator leader. The leader could assign others to be moderators of that forum. Here are a few ideas for it:
* Admin could set a limit for the maximum number of moderators that the forum leader may assign
* Could be set to require admin approval
* Forum leader could be given a choice of either directly adding their name -or- assigning them to one or more groups that the Admin has made available for that forum moderating team. (The member group(s) would be added to the persons secondary groups)
* If adding directly, could only grant abilities that the Admin has made available to that leader to assign. (This could be a different set from what the leader has for themselves)
* Only the leaders name would appear as the forum led by, optionally with the group(s) name(s).

yes on 1,3 and

#2--> Yes - hide it but optionally have it show the members of that group instead

Yes. We need a way of showing secondary user groups. It should be quite easy to do and should be a user option via a checkbox on the memberslist when the search by group. Ace suggestion.