This is what I've done using a variety of resources and now this is what I've got. I started with 3 hand raised chicks and when they were 16 weeks old I bought 5 one day olds and brooded them inside until they were 5 weeks old, then segregated them with chicken mesh inside the coop. They lived there for 2 to 3 weeks, during which time I'd let them out during the day and supervise most of the time. They had plenty of places to hide where the hens couldn't fit. The hens would chase if they could and the Australorpe, in particular, was aggressive, while being 3rd in her own little flock and peaceable. Now I have 2 flocks and a certain amount of mayhem every night in the coup. I segregated the new ones at night behind the mesh for maybe a month and then would leave the mesh open, but keep some obstacles up so the big hens couldn't get back there and just recently took the mesh off and added 2 new roosts, lower than the established roosting plank used by the big girls. I have 5 eight week olds - sussex, RIR, silkie - who stay on opposite side of the yard and forage all over under brush, and three 24 week pullets (all laying now) who ignore them most of the day but when coop time comes I have loud, nervous peeping chicks terrified of the older ones coming in and then some pretty determined pecking and actual screams, then the 3 fly to their roosts and stay and the others never quite settle (monster in the closet is real!!). Two found the curtained nesting box and hide out of site in there. I have nooks and low and medium high roosts available for the young ones. Last night I did some rescue maneuvers because the young ones wanted to roost high on the farthest end of the big girls roost, but same board. the leader came over and started pecking and knocking them off. I used two fingers and a thumb and came from above and "pecked" the leader. OMG, she was frozen right where she was and didn't move at all, with her head on the board. She tried again and so did I and then she walked down to her side of the roost and took it out on the second in line, pecking and picking at her so she hid her head under the third's breast feathers. I then put up a privacy curtain between the two ends, cutting the roost in two visibly, and the newbies were all in a line, closing their eyes quiet, and the leader was cuddled with her two but occasionally sounding off with annoyed, low throated- bahhhhhhhhh. Do flocks stay separate? Have I unwittingly made matters worse by putting up the curtain? I have only a backyard, and a roomy coop for them. I want to add a couple more in the spring but want to iron out all the wrinkles I can before another attempt.