Going from 3 people in house to 7 people....how do i..?

I can understand that this may be very difficult for you. Having a your brother's family lose their house and asking them to do their part of their share firmly can be very difficult. Especially, if it involves your family. It is always easier to be firm with a child, but remember, it is family. A brother and sister can be the meanest to each other and still be closer than ever. With family, everything is forgivable. So, don't think that you are over thinking it. Although, they have just lost their house, they still need to respect your mother's house as well. It is only fair and if you can just talk to your brother and his wife alone. There is no need to involve your mother because as the mother/grandmother, she will most likely say, "its okay" when really, you know it isn't. And as the daughter-in-law, she should be MOST understanding by picking up after kids, husband, and herself. So, I suggest that you talk to your brother and sister-in-law, so, it's an adult conversation. Say everything you need to say. Your logic sounds reasonable, but if they neglect to understand, then, be firm. If you've tried suggest nicely the first time and they still continue to ume that your mom will do everything, then, be a ***** about it. If the two adults need to learn how to clean up as if they were children then teach them with their kids in the same room. They're bound to change.