What happens to the briefs if a Rep changes Managers?

If a Direct Report changes managers, his/her briefs move with them. While the new manager will be able to view all of their previous briefs, the manager will not be able to send a deliverable, like, or comment on any past briefs.

To view any of the direct report's past briefs you will need to uncheck the "view closed briefs" box and scroll to the brief you wish to see. 

The brief is closed, so you cannot comment but you can see what was said.