Well a lot depends on your set up. Do you have a run? Does it have hideouts, and roosts in it? Is there multiple feed bowls?
Some of you have a great deal of patience. I do not. There is a huge difference between adding one or two birds and adding 10. It is rather exhausting to chase 10 birds, and the older girls will quit sooner. Adding 10 at once, spreads out the pecking so to speak. Where as one or two new birds will get pecked by everyone.
I have two ideas that work pretty well for me:
So what I would do, is put the cage in the run. Then I would let everyone out. The most aggressive of the older birds - I would put in the cage. Your older birds outnumber your younger birds, so you should be able to put enough in the cage, to get the numbers more one to one. Leave them like that during the day, see if they will all go into the coop at dark. If you let the free ones go in first, then wait a bit, then let the ones in the cage out, they will go into roost in a dark coop.
Or
I would let the old birds out to free range, and put the new birds in the coop/run set up, so that they can explore, without being chased for their lives. Then as close to dark as possible, I would let the old girls back in. The urge to roost is stronger than the urge to fight. I usually let them out in the morning, and back in at dark for a couple of days. But a little later, and a little earlier each day.
If you get some heartless bird or birds that will not quit - well they go in the cage.
All this being said, I have a large run, a lot of hideouts, multiple feed bowls, and multiple roosts and wind breaks in my run. That is important too.
Mrs K