reluctant to roost with the big girls

[peartreehens]

So I had an established mixed flock of 8 hens. I integrated 4 chicks that are now about 12 weeks old. No one's pecking at anyone anymore, except very occasionally. My chicks, though, are very very reluctant to roost on the actual roosts in the coop. I installed another roost to ensure enough room, but they still try to sleep on the front ledge of the nest boxes. Every night about sundown, I go out and evict them, stick them up on the roost, and they stay there all night, even if it's still twilight. I really don't want to direct the sleeping arrangements every night. The big girls don't peck them on the roosts anymore (though they did the first week or so). Will the littles figure it out? Do I need to block off nest boxes at night and try to get out there early enough to open them up? Other thoughts? Suggestions? thanks in advance.