The question

My father in law ask me to invest with him in constructing an investment property on his land. How do I secure my investment and returns if there is a future dispute amongst family when he is gone? I want to be properly informed on the options available to me with regard to an agreement before discussing my interest further with him. According to him This particular property is not attached to any estate planning or agreements and a sale is out of the question. However it may be a great investment opportunity.