I just hatched my first set of chicks under a broody on October 17th. I think I was probably over-protecting the whole process, and I will probably lighten up next time.... But for my first time, I guess I wanted to "hover" a little bit and make sure everything went okay.
I have 16 hens that are locked in a 8x10 coop/12x20 run at night but free range all day.
At first, I left the broodie on her nest in the coop along with the other 15 hens having free access to the coop. I had 2 broken eggs right off the bat, and was afraid it was due to the other hens messing with the nest when mama hen was off it. So I locked the other 15 hens out of the coop and kept the mama broodie hen in the coop by herself. I had 2 more eggs break, so I think it was probably a clumsy broodie issue all along, and not the other hens.
Since it was a bit chilly for newborn chicks outside when they hatched on October 17th, I kept the whole family locked in the coop with a heat lamp. I had to strip the coop of ALL shavings on the 2nd day because the mama hen was digging and scratching all over, and literally buried the waterer and feeder. She had 3' piles and bare floor. Crazy.
I let the chicks and mama into the run at about a week of age. Still hadn't introduced the rest of the flock to the chicks.... I had them locked out of the run during the day. Mama and chicks still had the coop to themselves at night, too.
Somewhere after the 2nd week of age, I started letting the mama and chicks into the run with the other 15 hens. Mama hen literally whooped all the other hens' butts, and NOBODY comes near her chicks now.
On Friday, I let the chicks and mama out to free range with the rest of the flock, and everybody is back in the coop together at night to sleep. One big happy family.
I haven't had any aggression issues with the other hens, but my mama hen is downright vicious. I don't expect any problems, but if she were a meeker submissive bird, I could easily see there being problems.
I did switch the entire flock to chick starter now that everyone is together. That means I need to keep an eye on the free-choice oyster shell feeder for my layers. I used medicated starter for the 1st week while the chicks were locked in the coop, but now I am using non-medicated starter.
That's been my experience so far... It has been a blast to watch the mama and babies together. I've been neglecting housework and just sitting outside and watching them. I hope I get the opportunity to hatch some more.
My little "family" is 5 chicks that hatched out of 13 eggs. Next time, I won't put so many eggs under her. I am not sure how well things would work out if all 13 had hatched. It might have been too chaotic for her to keep them all safe. I think 5-7 is probably a good number for my set up, but other people may have other experiences.