Commercial property purchase?

My father in law has a proposition for me to buy the siblings out and own 35% of the building. I dont see moving back inside, but I guess I would have FREE outside parking and a 35% investment on this building and lot, located in a prime commercial area. I can afford the 35% buy in, and my exp. for the build.(tax, insur) would get covered from renters. How does this process start? DO i need a purchase agreement drawn up? Its a bit confusing, but the 3 siblings own 2 properties, and my father in law is signing off on the other and the other sibling is signing off on this one. I am not using a loan, I have the money, so it will be paid for. What do I need to do to make this deal legit, and protect myself. Is it as simple as changing the deed, and a small document stating my % owned? I trust my wifes parents....especially since she will also be listed on the deed. Just need to know what processes we need to take to get this property transfered correctly.

Also, Do i need a purchase agreement? If so, who does that, buyer or seller, and what cost? I at least want some sort of reciept of purchase to show what I paid for my % of property.

PS Oh, and the other sibling, claims she;s not paying her half of the property tax either.. Its due at the end of August, she has been a 50% owner since Jan. Dont summer taxes go from Jan to July?

this is one where an escrow company can save your a((( Open an escrow and ask them to handle the sales paperwork and title searches. explain the situation to them and don't worry about paying them. Its worth it in the long run. And she owes the taxes for the time she owned her percentage and the escrow company will prorate it. That will probably pay for your fees right there. Some of the family deals end up being the worst messes. CYA

It would probably be wise to find a value on the property and determine income before you jump and..... make sure the contract specifies that you have the right to inspect the books or that there is an independent auditor or accountant checking at least quarterly.