Several different things could happen, when you first integrate the chicks and later when the cockerel goes through puberty.
I don't know what your plans are to integrate the chicks. Sometimes that goes so smoothly you wonder what all the fuss was about. Sometimes it ends in disaster. If you have an integration plan and am happy with it, great. If you want to discuss it, we can.
When the cockerel hits puberty the pullets should be old enough to act like mature hens. No one can tell you what will happen but there are many possibilities.
The cockerel could take over leadership of the flock with no drama. I've had that happen a few times. Part of that has to do with the cockerel and his personality, part of it has to do with the personalities of the hens, especially the dominant hen.
Your cockerel may show interest in the two pullets first or he may not. If he does, they may cooperate or, more likely, try to run away from him. He will probably try to force them. I've never had any pullets actually hurt with this but it can be hard to watch.
At some point he will want to mate with the hens. Some hens may willingly accept his advances but often a mature hen wants the potential father of her chicks to behave like a suitable mature father. Most young cockerels can't meet that standard. Some hens run from him. He may or may not chase them. If he catches them he may force them to mate. I've never had a hen injured from that but it is by force so injury is a possibility.
Sometimes the hens fight back. I hardly ever see this but it can happen. Either one could win the fight.
What I have seen a few times is that the dominant hen will not allow him to mate another hen in her presence. Mating is a dominance act, if she lets him mate in front of her she's losing some of her power. She will usually knock him off if he tries. Usually he runs away, at least for a while. But eventually he matures to the point that he fights back and often wins. That can be a quick skirmish and no big deal but I have seen it carry on for a few days and get really vicious. The worst case is when the cockerel doesn't have that strong of a personality and she does. No one got hurt when I had that but one easily could have.
These are the main possibilities I can think of. There are variations off of any of them. Sometimes the drama is less than I make it sound. Sometimes it can be dangerous. I think these things tend to go a better if you have a lot of room. Them being crowded seems to magnify any bad behaviors and enhance the drama. You can still have issues but they don't seem as bad with more room.
People go through this all of the time and it usually works out. There may be drama involved, there may not. Good luck!
mine were several years old already and had never lived with a rooster before so it was a big change for them. But yeah. They do eventually work it out but don’t be alarmed if there’s some scuffles at first. As long as there’s no blood or anything and they’re not keeping them from food and water or anything like that, I’d let them work it out.
