OP, you just described the saga at our house! We've resorted to Rubbermaid bins, and everything is dumped into them. Legos are separated from Playmobil, and the castle has its own bin since it's so large, but men and all their gear is mixed together no matter what line it's from. Our big rule is Legos and Playmobil cannot be out at the same time; it's one or the other. They are finally starting to follow it, and they are less frustrated now.