I have 4 hens that were raised as chicks - now 18 months old and pretty peaceful and friendly. One of these girls went broody in May and hatched a clutch of borrowed eggs and we kept two of those chicks. The chicks are almost full grown-sized now (almost 4 months old) and the adults still viciously peck at them while they are our free ranging together during the day. The two youngersters roost in a tree in my backyard while the adults always roost in the coop. I do have a tractor that I used to protect the chicks when they were younger - and I sometimes let them free range around the yard without the adults - and when there is enough space to get away - there isn't much aggression when they are all out together. Within a few weeks it might be too cold at night for the youngsters to roost out in the tree - but I don;t think that the adults would let them come into the coop. Do I need to build a small 2-bird coop for these youngsters until the adults accept them into the flock?
I think if you make a coop for the two, they will never fully integrate... It will always be US in this coop, and THEM in that coop. From what I've read, a flock sees anybody COMING INTO their territory as invaders. So, if one "flock" comes out of their coop, and they see "another flock" coming out of a different coop, they might be classed as invaders. About the only thing I can think of is getting up in the middle of the night and moving the pullets into the coop. You might want to leave the door open so they can escape in the morning if need be, or be there before they all wake up. You might have to do it a bunch of nights in a row. How big is the coop? You might need to lock them all inside a couple days so the pullets think of it as home. (That's the suggestion for when you move adults to a new home.) If you don't get the pullets used to going into the coop, they won't go in to lay eggs. They'll just make themselves a nest somewhere outside.
