I know that my p-doc told T (well, she already knew) and MC about something major that happened with me because my T told me. They also have weekly clinical meetings at their practice with all the T's/p-docs (I think there's like 10-12 total), and during that, they have a period for "cross-talk," where if a T wants to ask one of the p-docs about something going on with a mutual client or share information, they can do that (that's where p-doc told T and MC about the thing with me). And I know they sometimes discuss people anonymously, because my T told me she asked a question about a reaction I may have been having to my medication without identifying me, and my p-doc at the time answered (without knowing it was me).