We purchased 4 pullets from a breeder. One ended up being a roo so they swapped it with another pullet. The existing are about 8 weeks and the new one is around the same age. The breeder didn't mention quarantining first and just placed the new pullet in with the rest as if it was the norm. It was night so they settled down on the roost & fell asleep. However, the next day when we got home from work I noticed that one of the pullets was being aggressive to the new one. Constantly pecking at her head when she walked by & would chase her away from the food. One other pullet pecks at her this way too put only occasionally. When I go in the coop to check on the new one she jumps in my lap or on my shoulder. I don't know what to do. Should I leave them & see if they eventually start to get along? I tried to close her in the coop to keep her from the others but she kept trying to fly & hitting the walls so I don't think putting her in a dog crate would be good. She's very sweet & I'm concerned her disposition will change. Any suggestions? This is my first flock.