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How old are the Black Stars? That could help with the answer. And the way I read this, they are all female. No males around.
You have two different things to worry about. First is pure integration. Chickens can be territorial and defend their territory from any invaders. Sometimes this is not a problem at all but sometimes it is. If you house them where they can see each other, they will often learn to accept each others' right to exist, but sometimes you get one or more hens that just have trouble accepting newcomers. Housing them where they can see each other is the only way I know of to get beyond this point. Sometimes this part goes so smoothly you don't know why you were worried and sometimes it gets real nasty and dangerous.
The other issue is pecking order. Once they get over the integration issue, they have to sort out who has the highest social ranking. If they don't know this, it has to be determined. Sometimes this involves fighting, but a lot of times it is pure intimidation. One pecks the other and the other runs away. They have decided who is on top. Usually this ends it, but occasionally you get a hen that is a pure brute. They seek out to destroy other weaker chickens. That's when it really gets hard.
A more mature chicken will dominate an immature chicken. That's why ages are important.
Each chicken has its own personality and each flock has its own dynamics. You really never know what is going to happen with individual chickens or with individual flocks. Remember, we integrate new chickens all the time and it is usually successful, so don't get discouraged. You can do some things that will help your odds of success.
Maybe house them side by side for a while longer. Provide different feeding and watering places for them when they are together so you can cut down on potential conflict areas. Give them as much space as you can so the less dominant can run away and hide, even avoid the others. Or give them extra perches so they can get above the others or things to hide under or behind. I find it helps for them to have different sleeping areas. Mine often get really brutal on the roosts when younger ones are around.
Often, one or two hens are the ring-leaders. If you can keep them out of the equation for a while, things just might go smoother. There are a couple of different strategies around this. Either totally remove them somewhere in total isolation from the rest for a week or so. This will knock them down in the pecking order so when they come back, they have to spend their energy trying to fit back in with all of them, so they don't just pick on the newcomers. Sometimes they don't make it all the way back to the top either after you do this.
Anothe possible strategy is to pick a few of the milder hens and let them range with the newcomers, either out free ranging maybe in the newcomers territory so they don't feel territorial. As they work it out, add a few more hens.
It's not always this hard, but sometimes it is difficult. If there is an age difference they will not hang together until they all grow up. In this case, getting them to fairly peacefully co-exist until they mature is considered a success. The more mature will always dominate.
I agree with Gritsar to a point, depending on their age. If they are about the same age, let them work it out as long as blood is not drawn, but give them room to get away.
Good luck!!! And again,