Now you are getting the hang of it!
The Niles speaker selectors are redundant and they are not impedance matching so I would not use those.
You have way too much amp power. The volume controls are really 42 watts each, so you will easily blow them with these amps.
What you really needed was a six channel distribution amp.
If you use this gear you will have to be very careful, or you will have smoke and fire.
Personally I think to use those amps in this application is hazardous and may well void your home owners insurance in the event of a fire.
If you do use it put five pairs of speakers in the three rooms.
You will need three more of those impedance matching volume controls, two for each room if you want stereo.
Follow the instructions to wire the volume controls so that each of the five sets if speakers presents an 8 ohm load.
Use the front right and left output of the receiver for one room, use the crest for another and the Peavey for the third room.
The volume controls go to off so you don't need a switch in the rooms.
You can switch off a room remotely by switching off and amp.
Connect the crest and Peavey amps with a couple of Y-connectors to the front right and left pre outs of the Yamaha.
I would return those amps and buy a six channel distribution amp of 50 to 100 watts rms per channel.
I regard you current plans as dangerous with an inappropriate equipment list for the intended application.
