That may have been one of my posts you were reading. I don’t always say things as clearly as I should, but my posts are often too long anyway. The older hens might pick on them, they might not. “Might” doesn’t mean they “will” especially if you have plenty of room on the roosts. The more you crowd them the more likely you are to have problems, but you said you have room.
Other than sometimes during puberty, about the only time I see any bullying or brutish behavior is on the roosts as they are settling in at night. That doesn’t mean I always see brutish behavior on the roosts, just that if I see it that behavior probably comes on the roosts.
I’ve had several occasions where a broody hen took her chicks to the roosts and they slept there under her protection. But when she weans them and leaves them on their own, they often, not always but often, leave the roosts to find a safer place to sleep. That can be the nests. I’ve even had some chicks like that start trying to sleep outside the coop. They are just looking for a safer place to sleep.
I regularly introduce 12-week-olds from my grow-out coop to the main coop. Although those chicks were used to roosting on the roosts in that grow-out coop they normally don’t join the older flock on the main roosts. Sometimes they do but normally not. Since chickens normally like to roost on the highest thing they can, they often sleep in nests.
These things happened so often that I put up a separate roost, higher than the nests but lower than the main roosts and separated horizontally so they can find a safe place that is not my nests. That has saved me a lot of grief. I’m trying to advocate providing them enough room on the roosts so they can find a suitable place to sleep. I’m also trying to give a solution to people that complain about chickens sleeping in the nests. There are usually reasons chickens do what they do and crowded roosts, especially when you are integrating, is often a reason for chickens to sleep in the nests. You said you have plenty of room for them so you solved that problem. They don’t have to squeeze in with the older hens.
I’ve had chicks younger than yours that were used to sleeping in a separate cop move in on their own. I’m not sure what causes that but sometimes they do. You may have something else working too. My pullets often truly integrate into the main flock of older hens at about five months. That’s normally when they start to lay too so there may be a connection. Hopefully you will get a pleasant surprise soon. But they have finally matured enough that they can start making their way into the main flock pecking order. Those two are probably still sleeping off to the side with some separation from the older hens but yours are transitioning from two sub-flocks to one flock. They’ll be there soon.
You made the right call to leave them in there.
