We usually don't have trouble integrating our littles with our established flocks, but one time we did. We had a bossy hen who decided she needed practically the whole roost at night and wouldn't share with any of the littles. This went on for a week or two and we finally took (I think) @aart's...
Thanks! I started out with just Easter Eggers for thr blue/ green eggs, but I've branched out. Love the dark brown "chocolate" eggs, too! So much variety, it's just amazing! They're cool when they're grown too, though, such interesting personalities.
COckerels (young roosters) usually do better in an established flick, with older birds to teach them manners. Bratty ones make good soup or dumplings if you can't rehome them.
Wire to wire is good. This is what we call a "see no touch" setup. The chickens are close and can see, smell and hear each other, but they can't physically contact each other. Perfect for integration purposes. Keeps the bsbies safe.
We have a smaller pen for the littles adjacent to the big girls' run, and they are side by side like this from the time the littles are three weeks old to about six to eight weeks old. Then one day we open the gate between them and nobody even realizes they are hanging out together with nothing...