The "babies" are out with the "big girls" now, and everything seems to be going well.  There's always a risk that one of the older chickens will bully the smaller ones, but so far they seem to be coexisting just fine.  I still have to put the babies to bed at night - they insist on roosting outside the coop and I pick them up each night and put them in the coop to sleep.  Eventually they will get the idea where they need to sleep.