Expansion Pack

Our family is expanding. Nope, no one is engaged and no one is pregnant. In a couple of weeks, my daughter and her family will be moving in with us for a while. So we are in the midst of trying to clear out as much unnecessary stuff as possible, rearranging some rooms/spaces to allow for three more people in the house, and wondering how much baby-proofing we need to bother with (or will Alia just circumvent our attempts?).