Very normal, your birds are working out their pecking order, which I think you well know.
Been raising birds for 30 years here's a few things I do.
1- separate them but let them see each other, they'll get use to one another by sight. If they can approach one another with wire between them even better.
2- do a little free range in backyard, let one group out then the next. Plenty of room to run and or hide if necessary, and they'll get some good interaction.
3- adding one dominant bird in with the lesser birds can also gain acceptance by other birds. But there will be a reckoning when the dominate hen's are put back together, usually even if their nest mates the birds will see each other as strangers and they will reestablish the pecking order. Good thing for the lesser birds they'll be pick on less as the dominant birds work it out.
They best method I have found is when the younger birds are 5-6 weeks old move them into the coop with the older birds, but keep them SEPARATED. Make sure they can see one another and interact between wire, usually the older birds ignore them or pretend to. Add one of your lower hens on the pecking order, bottom one works best. An hour or two a day, she won't know what to do with herself in her new queendom. But she will be the most likely to take it easy on her new minions, but keep an eye on her. Leave her in longer every day, but make sure you let her roost and eat before she roosts with the older birds, or she'll have to get re inducted into the flock. After a week add another lesser hen and so on, they may not play nice all the time but eventually they become one flock.
It take's patience, free ranging them together I cannot say enough about, they can stay separated and yet there not. And when treats come out they'll forget about who's who for awhile. Please remember free ranging opens them up to risk, my rule is if I can't watch them or hear them they stay in the coop and run.
Every one gets attached to their birds, and when the little dinosaur comes out it can be shocking.