Adding Groups in and of itself in vBulletin is not that difficult. What is problematic is that new groups have implied permissions.
If you add people to a new group, by default that group will have access to private forums - probably not the most desirable result. It certainly was not for me.
After you create a new group, you need to run through your forum permissions one by one. Top Level permissions are inherited, so if you need an entire set of forums set to access denied, it is sufficient to set that permission level on top level discussion forums.
The way I had things arranged, I had all private forums under a single top level parent. I created a new group and auto-promoted people with more than 10 posts to have access to that group. The nasty side effect was that instead of having access to a single private forum, they were provided access to all private forums.
So... step 1 - create the group. step 2 - set permissions for the new group on ALL forums. step 3 - add members or implement auto-promotion techniques as needed.
It's not that difficult, but it does need to be stated. Showing people private forums, and then taking that privilege away once you notice the traffic is a bad way of running the show.
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