Me and my wife are building a granny house on my parents property. The property has no debt and valued at $1 million. My parents want me to do this. Me and my wife are taking a 100k loan with arab bank to build the granny house and we will spend another 30k cash to get it all done. Me and my wife are going to pay for it all. My parents have told me that the money is safe and if the house ever sells or they pass away the cost of the building that we paid for will come back to us first. We are only proceeding with the build on that basis. I need to have it be formal so no one in the future changes their mind and i lose our hard earned money. I have 2 brothers.
Whats the best way to go about this and whats the cost?