I like to have the broody and her eggs in a big dog airline crate in the coop, and let her out with the others when the chicks are five to seven days old. They go out when the flock is out free ranging, so there's plenty of space for everyone. Lots of space is very important to prevent disasters. Mary
My always broody hen is very hard to move. After several attempts to separate her, I gave up and just gave her chicks in the main coop. She did great with them and never had any issues with any other chickens. She did lose one after about two weeks but they are free range and I think a stray cat or hawk got it.
Just take the same precautions with water that you would if you had them in a brooder. I have a baby pool set up for my ducks and it didn't even cross my mind that a chick could jump in there. Luckily it wasn't full and we heard the chick screaming. She was fine but it could have been worse...
My broodies hatch in the main coop, normally keep them in the main coop a couple of days after hatch, and bring them back into the main coop to spend the night. After the first couple of days inside they pretty much spend all day outside.
When I consider my main coop too crowded I sometimes putt he broody and her chicks outside in the run in a small coop. After a couple of days locked in there I turn them loose with the flock. The broody takes them back to that outside coop at night. When the population goes down in the coop (I process some cockerels and sometimes pullets) I move them to the main coop.
I keep water and food at a level the chicks can reach it in the coop and in the run, but they also have a big grassy area where the broody keeps them all day. A problem in the coop is that chickens scratch a lot. Bedding gets thrown into the water. So I put down a large piece of cardboard (think refrigerator box) on top of the bedding and put water on top of that. I have to clean off that cardboard every day or two. The chickens do scratch a lot.
I put water in a small fairly shallow dog bowl and fill that with rocks for them to walk on. That way they don’t drown in their water.
I do a similar thing - mini-coop for mum and chicks inside the main coop. Mum takes them into mini coop on a night time while the rest of the flock roosts. When she feels they are ready, she takes them to roost with the flock. I usually let the chicks out at 2 to 3 days old to free range with the flock and the adults only seem to begin to teach them chicken manners when they are 6 weeks old so as little ones they seem to be fine.
I gave my broody several week old chicks. She took great care of them! They stayed in the main coop with the flock day and night without any issues. I agree with a statement from above- give them plenty of room. When it comes down to it, they are farm animals, do your best to provide shelter and food, they will do what comes naturally.
I installed a dog pen inside my coop to raise chicks. Putting a broody hen in with some new chicks and letting her raise them takes all the work out of it and she continues to protect them as they move into the flock.