If you are buying a house, it is important to have everything that is important to you in writing. Want the owners to keep mowing the lawn until closing? Get it in writing. Want that beautiful light fixture in the dining room? Get it in writing. This is fairly common sense, and when it comes to buying from a stranger, most people expect to do this.
It gets trickier, however, when you have family members involved. What if you are buying your parents’ house? What if you are adding your new common-law spouse on title? What if you are buying a property jointly with a sibling, and one of you is putting in more money?
I have found, over the years, that when family is involved, it is even more important to put it in writing. When things go wrong among family members, they go very, very wrong. If you are doing anything out of the ordinary, write it down.