Co-brooding is awesome when they can work out the details. Some hens love it, some not so much...
The black one is a bit more unsure and gets aggravated at the other hen because she can and does call the chicks out and tries to steal them.. Its comical to watch, all 9 of the chicks go back and forth between the two. When the first broody's chicks hatched we took 7 of them as it was chaos in the coop ( Thunder storm) the whole flock ran in and chicks scattered.. we left her with two. We haven't removed any of the newest ones but will probably take two that are extra cool looking.