We just got 5 chicks, 4 Plymouth Rocks and 1 unknown, which I think is a Brahma because it has feet feathers. They are still just a few days old and still in a starting box, but we are in the process of building their coop. The laying box is a 2'x4' rectangle with 12" walls. Should we put dividers in the box or is it ok to leave it open? The most chickens we think we will ever get is 12 or so, if that helps. Thanks in advance.