Hey, Cjeanean - I'm no expert, but if I have to mix new babies into my little flock I always provide some low shelter (low enough that the big roosters/chickens can't get under there) for my itty-bitties to hide under and behind if they are being threatened. If you come out and they are all clustered under or behind their shelter, you can probably assume that they are being picked on. Chicks are quite valiant about exploring any new environment, so if they are huddled under the protection and looking miserable you can guess the problem. Oh, and I also make sure there's a little water and food under there so they aren't trapped in the heat without hope. It does seem to be easier to put the whole gang in there at once - I think the numbers distract the older birds from attacking any given one.
Sybil
Sybil