Chickens & Ducks: Is it possible?

OK. I want to breed different breeds of chickens and ducks,I don't want to pen them all seperately, and I was just wondering if this is possible. If I rear a roo with two other hens from when they were little, will they, if I let them into a yard with other roos and hens, breed with only their "flock" (the three of them). Same with ducks. Will they go into a flock and only breed with the birds within their own flock?