Disable users editing their rosters

Hello all. This seems like a great community, and I have been googling this question for a few days. We have openfire set up on a test box, and before we deploy it to a live server, our admins just want to be able to disable users from adding more users to their roster. Right now we have shared group lists, but this does not stop someone from typing in a name under add contact and having that contact added.

Any help is appreciated, Thanks!