I can't tell you what will happen. Nobody really can. I can tell you a few things that might happen, but I really don't know what yours will do.
First, the question on the rooster and other hens. Some flocks have chickens, usually hens but it can be a rooster, that seeks out to destroy any weaker new chicken. Most flocks do not have these chickens, but they do exist. It is possible a hen would try to kill the other chicks. But what will probably happen (not for sure since some broody hens are wimps) is that the broody will teach any hen or rooster that threatens her babies a very rough lesson. Most of the time the rest of the flock quickly learns to leave those babies alone.
Not every rooster is a good rooster. But a good rooster will take care of all members of his flock, including chicks. I've seen a rooster quit what he was doing and go sit with some chicks that got separated from their mother until Mama worked out the concept of gate. "If I go back through the gate I just went through, I can get back with my chicks on the other side of the fence." Took her a while to figure that one out. The rooster stuck with the chicks until she did.
So, will the rest of the flock hurt the babies? Maybe but probably not. But there is something else working in a flock besides older chickens trying to kill the younger chicks. There is this thing called pecking order. Any chicken that is higher in the pecking order will peck a lower rankiing chicken if they invade her private space and she feels like doing it. Baby chicks definitely rank lower in the pecking order than any adult. I've seen two week old chicks leave the protection of the broody and stand next to the other adult hens, all of them eating. Sometimes the adult hens ignore the chick, but usually one decides to enforce her pecking order rights and pecks the heck out of the chick. The chick runs back to Mama as fast as wings and legs can carry it. Mama usually ignores this behavior. The older hen was perfectly within her rights to enforce her social position. This pecking order peck is not meant to injure the chick, and it usually does not. But it is a bigger chicken pecking a smaller chick and the chick can be seriously injured or even killed. So there is some danger from that, but not a whole lot.
Now, lets discuss the multiple broodies. Many people successfully let multiple broodies raise chicks together and have no problems. Sometimes each broody keeps her own chicks separate and they ignore each other. Sometimes they work together to raise all the chicks. Sometimes life is good.
But sometimes it does not go this well. It is possible that one broody will try to kill the other chicks and Mama may not try to stop her. But usually Mama will try to protect her chicks. That can get pretty rough. Chicks can get hurt just from the fight.
Sometimes one broody thinks she is the perfect mother for all the chicks. It does not matter if there is a difference in age of the chicks. She tries to take the chicks away from the other broody. Naturally, this results in a serious fight. Again, chicks can get hurt in the fight.
What will happen in your circumstances? I don't know. As I said, many people are successful with multiple bropdies, but sometimes there are problems.
Good luck!
