I agree with Rosemarythyme. What I typically see is until my pullets start laying I have two sub-flocks. If the young invade the personal space of the old they are likely to get pecked so they quickly learn to avoid the adults. Sounds like yours are normal.
How big is your coop and what does it look like? Do you have enough room in there for a second roost? Can the young ones get somewhere to avoid the older while they are in there? I do this so often I put in a "juvenile roost", horizontally separated by about 3 feet, about a foot lower than the main roosts, and higher than the nests so they are not tempted to sleep in the nests. Before I put that juvenile roost in they were sleeping in the nests a lot. I don't care where mine sleep as long as it is predator safe and not in my nests. When they mature enough they will join the adults on the main roosts.
When I open the coop in the morning I typically see the juveniles up on my 5' high roosts while the adults are on the coop floor. The juveniles have learned to avoid the old ones so things stay peaceful and no one gets hurt. When they go outside they keep their distance.