HELP --Splitting a house with In-Laws, what should i be aware of?

[Mike Xiao]

I am in discussions with my brother and sister in law, to pay off the remaining amount due on my mother in laws home.  The total amount still owed on the house is $230K, and the home is currently worth about $800K, conservatively.  My sister in law would live in the back house rent free, while my mother in law lives in the main house.

We would split the $230K 3 ways, and we would all be equal owners on the house. We would split propety tax, repairs, and utilities 3 ways  

Seems like a no-brainer but I am just weary of getting into any sort of investment with family and in-laws, due to all the nightmares I've heard.

I think I want to create a side contract for potential issues that arise, so there is no argument back and forth. We just turn to the contract

What things do you all anticipate that could possibly come up as a debate, that we should put into such a contract???