Will your other chickens and rooster hurt the chicks that will hatch in pen?

Yes, there is a possibility that the other chickens and rooster in the pen could hurt the chicks that hatch. Mature chickens can be aggressive towards young chicks, especially if they are not used to being around them. The rooster may also attempt to mate with the chicks, which could injure or even kill them. To ensure the safety of the chicks, it is best to keep them in a separate pen or brooder until they are large enough to defend themselves.