Allow specific usergroups to add members to?

[Rhellings]

Hello!

I apologise if this is already possible, or a thread already exists, I couldnt see anything that exactly described what I'm after.

Ok so alot of our website is made up from Clans and Regiments for a gaming community. Whilst I know there is groups section for Vbulletin, but correct if im wrong but the discussions here, do not appear as forum threads?.

So what we are using is forums for the clans and regiments that are hidden to members not inside the clans usergroup. Its working fine but we require the clan leaders to fill out a form that lets us know what members to add or remove, then we manually add the users to that usergroup. So my question.. is there a way or a mod, that could allow a specific user or usergroup to add other members to the usergroup of our choice?