In Groupwise Messenger we have set up a custom contact list that lists all
departments and users (so users can not change it). However, when
employees get added/changed/deleted, the custom list needs to be manually

What I really want to do is have Messenger show the tree structure with
the users in their various departments (and be dynamically updated)
without the client workstations being able to change this.

When I go to manual, i.e. custom, it makes everything manual. When I go
to automatic, I can't lock the user from changing the workstation setting.

Is there a way to achieve both objectives?