They could definitely coexist peacefully. I do wonder though if over time, the flocks might shift socially. Eventually, they might start to interchange nesting boxes, or try to all go to sleep in the same coop? And they would definitely intermingle mating-wise. So if you were planning to hatch pure breed eggs, that might be an issue. Honestly, I'm not sure?
I've actually just built a smaller coop onto the other side of my run, and built a removable divider in the middle of the run so that I can separate my flocks into groups for breeding. At other times, I plan to use the smaller coop as a nursery for growing chicks. I'm planning to let them free range at different times. When I want to integrate the flock, I can just take down the divider, but I was kind of wondering the same thing. If I take down the divider, will they all start sleeping in the same coop, or will they continue to sleep and lay in the coops they're accustomed to? I've always kept all my chickens together until now, so it's a big experiment for me. I'm sure there are folks on here who could answer all our questions.
