Plan on changing sheets once or twice a day when their newborns..and daily after that as they sleep through the night. You might want to have a shower just for bed, and bath. Let everyone pick out their own theme, and keep the room in neutral colors, so that they all will blend, and have a different look to change with.

Baby bedding is a serious things for all. So you should take decisions about this so carefully. I will suggest you to find out the forums about baby bedding. I can suggest you some of the links.