Ok, I think i'm going to get a pair of cb's

I'm debating cage set-ups now though. I have two nuns, a canary and then the pair of CB's. Should i build one larger aviary? (I'm afraid the canary would stop singing...and if the cb's get busy they would torment him)
Should I do three stacked flight cages? Some other combination?
What are your opinions? I think the cb's would breed, the nuns are two boys and the canary is a boy.
THanks!!
~olivia