Overriding previous signed document

My grandfather from my mother’s side expired around 2 years ago. He did not make a will. He owned a grocery shop that my second uncle (mother’s brother) operated right from the start. Since grandfather did not leave a will, after his death, the ownership of the shop went to all the 4 siblings instead of my second uncle. All the siblings agreed to hand over the ownership to second uncle without any demands and signed a document earlier in the year. But, somehow it didn’t work out. Since uncle was in a hurry, as he had to sell the shop, another document was signed, where instead of forfeiting their rights to the shop, it became a sale deed to second uncle. Since the other siblings never had any connection to the shop, neither in the past (no management, no profit, no income, no loss) nor at present, can they incur any liabilities regarding the shop? Or if uncle’s signs an affidavit stating the same, can they be saved from incurring the liabilities? Can the affidavit be made without the reference no. of the previously signed documents?