I've seen a flock literally tear a chick apart, once there is blood the frenzy begins.
I normally put newbies in a pen next to the coop or run for a while so they are use to seeing them. Then I try to move the set up inside the run. Even if my flock free ranges they still come back to the coop and run to lay and roost for the night so having the chicks inside the home territory but protected helps get them use to seeing one another.
Once I move them inside the coop I try to rig up something like the pic above, the little ones can get in but the big ones can't. I also leave the original "penned" area out in the run for them to get into to hide if need be. I put food and water in the area designated for hiding as well, just in case.
Once they are roaming around with the flock it's just a matter of keeping an eye out to see who is getting picked on the most and if they are going to survive it. Chickens are brutal. I wouldn't trust the hen that is interested in the babies she probably is thinking of doing damage not mothering. Typically it will all work itself out, the only time it didn't work for me was when I tried to introduce some frizzles that I had hatched out. The flock would not accept them no matter what I did and how long I gave it. Eventually one by one the flock killed them off. I still feel bad about it and it's been a few years past.
Best of luck
I normally put newbies in a pen next to the coop or run for a while so they are use to seeing them. Then I try to move the set up inside the run. Even if my flock free ranges they still come back to the coop and run to lay and roost for the night so having the chicks inside the home territory but protected helps get them use to seeing one another.
Once I move them inside the coop I try to rig up something like the pic above, the little ones can get in but the big ones can't. I also leave the original "penned" area out in the run for them to get into to hide if need be. I put food and water in the area designated for hiding as well, just in case.
Once they are roaming around with the flock it's just a matter of keeping an eye out to see who is getting picked on the most and if they are going to survive it. Chickens are brutal. I wouldn't trust the hen that is interested in the babies she probably is thinking of doing damage not mothering. Typically it will all work itself out, the only time it didn't work for me was when I tried to introduce some frizzles that I had hatched out. The flock would not accept them no matter what I did and how long I gave it. Eventually one by one the flock killed them off. I still feel bad about it and it's been a few years past.
Best of luck