Room 1 has a 7.2 Onkyo with Zone 2 capability.
Room 2 has a pair of speakers.
Room 3 has a pair of speakers.

Here's what I want:

I want to be able to play music in Room 2 or Room 3, and sometimes during get-togethers, play music in Room 2 AND Room 3.

I purchased the Onkyo in Room 1 with the intentions of utililizing the ZOne 2 capability, but, problem is that I have 1) three zones, not two, and 2) I'd like to be able to play room 2 & 3 simultaneously on special occasions.

I should also mention that I have a very basic Stereo receiver with Speaker A and B capability, as well. I've read in other sites that it is possible, with RCA cables, to hook up the main receiver (Onkyo) to the second reciver, and be able to play in three zones. (Anybody have more info on this?)

Problem is, I'm not sure if it would be possible to play Zone 2 and 3 at the same time.

Any help or suggestions would be greatly appreciated. I'd be happy to provide more info, if necessary...