it is bizarre, but I had two broody hens (different breeds) that I stuck eggs under at the same time. regarless of who hatched whom, the one hen eventually got all the light colored chicks and the other hen took all the dark colored ones. and they are cliquish...bigtime. that's why I started naming them after teenybopper movie characters from buffy and heathers.I have found that in flocks with multiple breeds, individuals of the same breed do tend to hang out together. It was a bit unexpected, but I've had it happen with 3 separate flocks. In one flock I had several birds each of three different breeds, plus one single bird of a fourth breed. The single bird kept going from group to group, looking for a place to fit in. Just another way that chicken flocks mirror the social structure in high school -- nothing but cliques and full of bullies!!
Seventy eight chicks!!! Wow, you've got your hands full.