I've had 4 or 5 broodies raise their chicks in with the flock. The mamas have done fine at keeping other hens away from the chicks. At night she would just cover them wherever they'd gathered, sometimes where I'd planned, sometimes not. Sometimes the roo helped the mama and sometimes he seemed to ignore the whole operation. One thing I really like about doing this is, when the mama is through with mothering, the rest of the flock is used to leaving the chicks alone. They tend to keep to themselves but they are safe. I just let them sleep huddled wherever they wanted til they decided to join the rest on the roost. All I did for the mama and babies was find some feed like flock raiser that all could eat, build some steps to the food and water with bricks and concrete blocks, and keep plenty of fresh hay around. That was it! It was a real pleasure to watch them grow up this way. I still had oyster shell out, separately. Never saw a chick bother it.
I don't know how cold it is where you are. I did have one batch hatch in a rather cold February, with temps below freezing at night and some days with highs in the 40's and windy. The chicks were outdoors with mama within the first week, anyway. They would run around maybe only for a few minutes before running under her to warm up, then in a few minutes they'd be back outdoors again. They did fine.
I've read accounts of broodies who wouldn't have anything to do with their chicks, though.
