During the season I usually have three or four different aged juvenile groups in my main coop. The adults sleep on the main roosts. The older juveniles sleep on my juvenile roost. The other juvenile groups sleep in separate spots on the coop floor. I let them spread themselves out and decide where they want to sleep. As long as they are somewhere predator safe and not sleeping in my nests I don't care where they sleep.
I seem to be posting this photo a lot lately. You are not the only one having issues this time of the year. I used to have a regular problem where juveniles were sleeping in the nests so I put in this juvenile roost. It is lower than the main roosts and horizontally separated by a few feet. Obviously it is higher than the nests. On the rare occasions a juvenile does try to sleep in a nest I just toss them out onto the floor to show them that the nests are not a safe place to sleep. I let them find another place to sleep that they consider safe. You only have the two separate age groups. If you have a segment of the roosts that the adults aren't using that might be a good place to put them if they start sleeping in the nests.
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I try to intervene as little as I can and just let them work it out. There are a lot of different things that can possibly happen. That doesn't mean they absolutely will happen. I try to not fix a problem before I have problem, if it's not broken don't fix it type of thing.
Your two age groups aren't that far apart. They may be OK sleeping on the roosts together. If they are not and you are not happy where they are sleeping then you need to do something. Hopefully we've given you some ideas that might work.
Good luck!