The babies do not have a broody mama, I've had them since they were several days old and used the mama heating pad. The hens have been in their tractor for several years with no issue. Once the chicks were big enough to be safe free ranging, I've let them all be out together. No issues, the hens would actually herd them into the adult tractor or under cover away from hawks, etc. I had one night over a week ago that it was pouring down rain and several of the babies got up on the roost with the big girls and, after counting heads, I just closed them up there for the night. They were all fine. Then I went several days with no eggs--until I found a clutch in the babies tractor. I clean both tractors every week and put down fresh bedding, but the hens don't need bedding all over because they roost for the night and only go back in to lay. So, the nest boxes got fresh bedding. The babies actually had lots of bedding to absorb the poops. I can't see anything making them feel safe/unsafe in one over the other--I think they are establishing their claim over ALL the space. This weekend, I plan to remove the bedding and clean as usual (and I move the tractor one length forward) and then I won't put new bedding for the chicks, only for the nests. If that doesn't do the trick, then I'll have to make a poop board for over where they are laying eggs. I don't really care either way where they lay but I'll have to keep the nest clean of poops from above. I don't want to make an opening to keep the hens out because the chicks go in and out of the adult house and, besides, the chicks at 8 weeks old are almost as big as the hens (most of them, anyway).