I know that a lot of people say this...but in my flock it has not been my experience. I have a large flock, probably 40-50 birds at any given time. I get new chicks every spring and sell the 1 year olds every fall. I start when the chicks are about 5 or 6 weeks old, putting them in a pen within the pen for a few weeks. Then I start putting them in the coop at night inside a small dog carrier so they can be seen and heard, but not pecked for a week or so. Then I open up their pen within the pen in such a fashion that they can come & go in/out but the older ones can't get in & , they're fully integrated by 8 or 9 weeks. I have never had a chick injured, but I do intentionally purchase "non aggressive" breeds.
It sounds as if they have established a pecking order, with the older ones dictating when the younger ones go into the coop. They will eventually tire of playing that game. Its tough to be the young second fiddle in a flock. The other cockerel is probably the dominate one and won't let him with his age mates and the older hens don't want an imature rooster around. Thats the way it is and with the other cockerel around, may always be. You don't give a number for the pullets but if the numbers are low there may not be enough females for two.
It's been a couple weeks since I've introduced everyone. It seems everyone is getting along better. Since the newer girl's seemed to be afraid of the ducks in the coop at night I have a barrier separating them and it seems to have helped a lot. My one Rooster that seemed to be getting picked on has been up in the "nursery" with one of my gal's (she hurt her leg) so he can grow a bit more before being surrounded by all those Hen's.
