Hello Malcomb,
I was looking to do something similar. I have two patio speakers I wanted as a powered zone for the Onkyo TX-NR807.
I downloaded the TX-NR807 owners manual from the onkyousa.com website.
I think the manual says you can have a 7.1 in the family room and define a second powered zone as two stereo speakers in your kitchen.
As long as you are not using the kitchen speakers you have a 7.1 system in your family room.
If you are using the kitchen speakers then you only have a 5.1 system in the family room.
You could watch a movie in the family room and listen to the radio in the kitchen. The remote controls volume for both zones.
When you are no longer using the kitchen speakers you have your 7.1 system back in your family room.
If you want to avoid losing the use of two speakers in your 7.1 system when using the kitchen speakers, then get an Onkyo TX-NR1007 that has 9.2 channels.
I was confused when you said you wanted 2.1 in the kitchen. I hope this helps, Good luck, ORF