Not sure I get the problem. If you want stereo music in three zones, then just switch the receiver to stereo mode. Party mode is only supposed to operate in the main room with the surround sound speakers. That’s the way it works with my current Yamaha receiver, which is eleven years old, and the one I had before that, which is fifteen years old. So I have to wonder – just how old is your “old” receiver?
Regards,
Wayne A. Pflughaupt