So my wife (before we were married) bought the house with her mother. The situation no longer is working. We met, married and had a kid. Her mom found a serious boyfriend. The house and situation was fine before but now there's too many people for not enough house with a baby and aging parent. Her mom used her inheritance for the down payment and significant upgrades to the house. My wife has been paying an equal share of the mortgage and other expenses since then. I've been doing a lot of the regular maintenance that my MIL was paying for before (lawn stuff, HVAC filter changes, little stuff like that but that my MIL was paying for). A lot of the furniture, appliances, etc were paid for with a joint account they set up. They would put a little extra each month into that joint account for that sort of thing. Tax returns also went into that account. When we talk to my MIL it sounds like she's pretty open to her and her BF buying us out. It's more house than they need and should take care of but it's what they want. Because of little man it's not really something we want to buy them out of since it's an older community and right on the water that has gators. They bought the house within 2 weeks of the very bottom of the real estate market roughly 66 months ago so between the market going up and the upgrades there's a pretty good amount of equity built up. Essentially it's going to have to be a divorce type split of the asset so how do we go about making sure we get a fair number since we are going to be starting over from nearly scratch?