I would ask each person "for future reference, is it okay if I repeat things you tell me?" Or if I want to share everything with all my partners, I would say "I don't want to keep secrets, it makes me feel wrong, so you can feel free to talk to me about anything you want, but don't tell me things you don't want repeated".
Doesn't mean I'd repeat things verbatim, mind you. I could go and tell A "I was talking with D, and they seem a bit frustrated, I think you two should have a talk" or tell D that directly ("tell, A, not me!")
I've never been in that kind of configuration before, but I work on the model of open dialogue, I don't want to ever feel like there is something I can't tell one of my partners.