I have done this several times successfully. It's my favorite thing!
I find that separating the broody beforehand helps. She may get aggressive towards interference once she has those babies. I actually section off a part of the run and use either a crate or the duck house (the ducks don't sleep in it anymore, preferring to stay in the coop with the chickens).
If you move her before you give her chicks, it eliminates potential problems with other chickens.
Other advice:
- Put the babies under her late at night in darkness.
- Be prepared to sit in the coop for a while and listen. Babies peeping and mama clucking = good. Silence = not good.
- Be prepared to take the babies out if mama pecks them HARD. She may peck a lil to get them tucked under her, but you'll know the difference.
- You can try a few nights in succession if it doesn't work on the first night.
- Have s brooder handy as you may end up raising them yourself.