it would be nice to have pair program with coworker and llm in a shared session.

I don't see the appeal of both. With coworkers I want to test that humans can understand the code and that we both understand the bigger-picture and agree that the code fits.

An LLM in that mix would be like an automated version of That One Guy who isn't really engaged or curious but keeps bringing up unhelpful stuff to justify their "work" during the meeting.