I've got old girls and also 14 week old chicks. I've got my coop split, but they can all roam freely in the backyard during the day. I'd seen an egg in a nesting box on the young ens' side - though it is possible for the old girls to crawl through the tops of the nesting boxes or come in on the little's door. I just found an egg on the side of my yard - typically where the littles hang out, but the older ones could go there, though I have no idea why they would pick there to lay an egg. Is it possible one of the young en's laid it? I'd say no, wasn't expecting the possibility of an egg for another month. The young ones I've got are a lavendar marans, a splash orpington, a white leghorn and a cream legbar. The egg is a light brown egg.