Property dispute between brother in law and father

Hello, I am from Bulandshahr, UP and my family is facing issues with land acquisition. The case is : My father, uncle and Brother-in-law had started a college in partnership and the investment amount has been taken as a loan. After a couple of months in partnership, my brother-in-law has raised a disagreement by saying that he was not in a position to pay the loan amount. Then with the consent of all the parties (that includes 3 partners and the society members under which the college had started) an affidavit has been submitted reporting the closure of the partnership with mybrother-in-law. But when a confirmatory notice has been sent to him, he objected the withdrawl from partnership by saying that he was forced to do that. Now, my father had received a notice from the registrar office seeking an explanation for the same. Also, my brother-in-law is threatening by demanding to be the sole owner of the property. My brother-in-law is the chairman of the society. What should we do?