Hens have been hatching eggs and raising babies with the flock for thousands of years. Some people isolate them, some don’t. There is no right way or wrong way, just the way we choose to do this. There are risks and benefits both ways.
You are dealing with living animals. Those don’t come with guarantees. No one, including me, can tell you what will happen. We can tell you what has happened. If enough of us do that, you will get some really conflicting stories.
The biggest risk of trying to move her is that she might stop being broody. The best time to do that is before you give her eggs to hatch, not after she has eggs. Many people do successfully move them, even at this stage, but some people have failures when they try that.
I let mine hatch with the flock and raise them with the flock. I have never seen a dominant rooster even come close to threatening a chick. I have seen a dominant rooster help a broody take care of her chicks. Practically all roosters that see baby chicks with the flock assume that they are their offspring. They may or may not help the hen with them, but they don’t attack them.
After a little initial curiosity the other members of the flock generally don’t pay that much attention to the chicks. If Mama thinks another flock member is threatening her babies, she quickly whips butt. On occasion another older flock member will threaten a chick, but most of the time I’ve seen a broody attack another chicken was because that chicken got close to her baby, not that they were actually threatening it. If Mama is not there to protect a chick, it is possible another flock member will kill lit, but I’ve never lost a chick to another flock member as long as a broody was around to protect her chick. I did lose one when a chick got into a grow-out pen with a bunch of 8 week olds and Mama could not get into that pen to protect her baby.
I wish you luck!
