I can't give any guarantees with what will happen with living animals, just about anything can happen, but I let my broody hens raise their chicks with the flock form Day 1. I have yet to have a baby chick harmed by another older member as long as the mother hen could get to her baby to protect it. I had a chick get inside a pen with several 8 week old chicks where the hen could not get in and those 8 week olds killed it. I have never had a mature rooster even threaten a chick but occasionally immature cockerels or older hens do threaten them. Mama quickly kicks butt when that happens.
Sourland makes a good point though. It is a lot easier on the Mama hen if she has enough room to work. Typically my broody hens keep their chicks separated from the other adults so there is less chanced of problems.
Another potential problem is what access to your coop looks like. If your coop is elevated the chicks can have problems using a ramp. They don't know to go out to the end of it and walk up, they tend to gather under the door and they can't jump/fly up. My pop door is about a foot above the coop floor inside and above the run outside. I built steps out of pavers inside and outside so the chicks could climb up. My chicks can fly pretty well by two weeks of age (I don't have breeds like Silkies that can't fly) so if your coop access is hard you might want to separate them for a couple of weeks. If you do separate them try to house them where they can see and be seen by the adults. And make sure they cannot escape confinement since they will be in danger if Mama cannot protect them.