DOCUMENT REQUIRED FOR PAYMENT PROOF OR NOT

We have a shop which is was on my grandmother name .. she died and legally it has 3 shares(my two uncle and my father) nBoth of my uncle died last year and their family later on released their share to my father .. RD has been registerednAnd my father paid in lakhs to the other party for releasing their share but the payment thing is not mentioned on papers. We have only bank transactions proof. Someone suggested us that we should geta document ready from notary mentioning all the details about compensating them with the particular amount for releasing their share to avoid any future conflictsWhat should I do in this case? And what should be mention on papers please help