I have nothing in writing, but I have 2 sons and a daughter and we've talked about certain things that will go to certain kids. After they get them, they can do whatever they want with them, trade or whatever.
My oldest gets his great grandma's grandfather clock, my youngest son gets the childsize rolleop that my fil used as a child, and my daughter gets my Kitchenaid mixer (1980 model), my stash, and her great grandma's oak highchair that folds down into a stroller