I like the ability to restrict users from seeing data only assigned to them. However, I want to be able to segment this more and create teams or groups. There is an admin of a group that can see all those contacts assigned to users of that group. If John is a admin of Group A and Suzy is an admin of Group B, then John and Suzy can see only those contacts that are assigned to them or the users of the group they manage. Finally, John could be an admin of multiple groups.