Integration of new birds in a small coop is tough. When those birds are younger or smaller, it's even tougher. Besides considering whether or not you have enough space for all the birds to fit once integrated, you need to consider if you have enough space for them while they are getting to know each other and sort out the new order of things. In the beginning my bantams needed a lot more space to feel safe around the big girls. They gave them a very wide berth. And the big girls demanded it, even the more mellow Buffs to some extent, giving some pretty sharp pecks and running them off. For a good two weeks I kept the bantams in a dog crate in the coop at night because there was just no way for them to get away if need be. Once some time passed and everyone knew that everyone else knew where everyone belonged in the order then things settled down nicely. When I noticed the bantams putting themselves to bed on the lower roost instead of hiding out in the crate I figured they were comfortable enough that I didn't have to worry. I still keep an eye out for any bullying though and do things like tossing treats and scratch far and wide so as to help avoid conflict.
They are all together now, it's been almost 2 months, and things are ok, I still however, put the silkies in a separate area at nite .
