I like to get them back with the rest as soon as possible. It makes reintegration easier and the chicks grow up as members of the flock right away. Just know that if you have another broody with chicks that is aggressive, she may attack another hen's chicks. I don't think it is the same with ones sitting on eggs, though.
she is fierce and if the dogs get near she goes into defense mode, so much so that she actually injured a chick so bad I think she broke it's neck and it passed right after. It was an accident. We don't allow dogs in the pen anymore. I'm sure the mom will teach them to keep their distance in the future with no fences between them. 
