I keep my broodies in a box about 30 inches square with a hardware cloth gate to keep the chicks in with her. They are usually satisfied to stay in there for the first couple days. After that the hens usually take the chicks around the coop for a few days while everyone else is outside (I open the chick gates and let the mamas do as they want). A few days later they usually take them out for free-ranging.
My biggest problem is that my run is made of 3x4 welded wire, so the chicks can get through but not the hens. So anytime they are in the run/coop and not allowed to freerange, I usually keep chicks and mom locked up, because otherwise the chicks walk through the wire outside the run and are exposed to danger, plus mama hen usually freaks out when that happens.
I have a roo I had to pen up outside the coop, and he's found the ladies will hang out with him since he offers them tidbits and let's the chicks in and out without bothering them, so he's now becoming my babysitter now that I've moved his pen to place with good arial covering.
SOMEtimes a hen will offer to peck at a chick, but it's very rare around here and the chick runs. My mamas are protective. The only chick-bashing I've seen is a couple of teenage cockerels are getting too close to one group of chicks and the chicks' mama goes after the young cockerels with a vengeance. Their mama has already left them to fend for themselves, so they manage to get in trouble at times.
