Suit filed by heirs claiming ancestral property

I would like guidance on the following property dispute matter: - In 2013, Mr. X purchased a piece of land in Maharashtra from Mr. Y - Prior to that in the same year, Mr. Y had purchased the same land from Mr. Z (currently alive) - Subsequently, Mr. X purchased the land from Mr. Y by paying Rs 15,00,000/- through cheque - Mutation entries in 7/12 are presently in the name of Mr. X and he has been treated as the recorded owner Now, after several years the legal heirs of Mr. Z have filed a civil suit claiming that the property is ancestral property Mr. Z had no absolute authority to sell it, and The sale deeds should be cancelled / declared invalid under Section 31 of the Specific Relief Act. My queries are: a) If the land had already been partitioned/sub-divided earlier, can the heirs still successfully claim it as ancestral property? b) Does the fact that mutation stands in the name of Mr. X strengthen his case as a bona fide purchaser? c) After 10 years from the transaction, can such a suit still succeed? d) What would generally be the burden of proof on the heirs claiming ancestral rights? Any legal insights on whether such a suit is likely to sustain would be helpful