Hi Maddox, thought you may find this interesting, as you know i keep my broodies in a separate house and small run, within the field where the others free range, once hatched I keep them there usually letting mum back to join the flock after approx 6 weeks (once she's had enough)! and then the chicks out approx 8 weeks, there is always a bit of bullying for a couple of days until they settle, but the chicks dont have any protection from the mum, as she's well and truly off without them!
So as an experiment we decided to let mum and 2 chicks out at 4 weeks, bingo! no bullying, mum protects them and shows them the ropes and they all live happily together! (still sleeping under mum in the big shed at night) so far we've done it with 3 hens and their chicks, its a real success!