Legal Heir of a dead Hindu wife?

Hi.. A property was bought my Mrs X in 1975. She dies in 1981. She has 5 minor children(eldest one is 11 years in 1981). Her husband Mr Y seels it to Mr A in 1982. Again one Mr B buys it from Mr A. There no legal doent that shows that Mr Y is the legal Heir of his wife Mrs X. But the sale deed mentions that Mr Y is selling the property for family Maintenance. Now id this sale deed valid? Can the minor children who are all majors now claim shares in the sold land? The land was transferred twice after the sale deed in question. What does the Hindu succession Act says about this?