You will need to make the little fenced area escape proof. Adult hens can and will snatch and kill any small chicks they can get at. Which includes pulling them through chicken wire. Ask me how I know.He escaped out of the little fenced in area I had for them and I found him dead in the corner. The cage is inside the run so either the turkey got cold and died or got attacked by the chickens and died.
So your chicken chicks are not safe either. Sure, they may understand their momma’s broody clucks better and come back when she calls, but she cannot protect them if they get out where the other chickens are without her.