When my new babies are old enough to integrate into the flock, this is what I do. It is just plastic mesh, garden stakes, and cinder blocks. I set up a pen in the run (usually it has a top on it...don't mind Ichabod...she thinks the straw on the baby's side is WAY better than the same straw I just put on the other side
) After everyone seems comfortable with eachother, I open the door, and let everyone mingle. Once everyone is used to this, and the babies are conditioned to return to THIS coop, everyone gets to free range again, and the baby pen gets taken down.