groups

Under the group manager, if one user is assigned to multiple groups, and the permissions of the groups are different, how to calculate the effective permission of this user?

I'm trying to setup a user group for our office admin. We are a really small office (just 3 ppl) so I want her to be able to see all voicemail, missed calls, recent calls, call routing, and ring group forward just like the superadmin dashboard, but of course without the rest of the superadmin...