Blondie, I don't think it matters if a person confesses to one other or to a group.
The whole purpose of privilege is that if it is revealed beyond that, then people won't feel free to reveal anything embarassing or confidential of the past, so those people can't do their jobs properly. Privilege does not extend to planning future crimes.
Privilege extends to other Psychiatrists, doctors or lawyers, pastors anyone else within that "firm" or "practice" or religious entitity.