I have 10 13-week old pullets. Two of them were added when they were all 9 weeks and have started roosting on the edge of the nesting boxes. They sleep on the roost at night with all the others, but during the day, they roost on the nesting box. The nesting boxes are built out the side of the coop. There are three of them. How can I stop this? No one is laying eggs yet, but when they start, it will be a problem, since the two are pooping in them. Thanks!