Can a son claim share in inherited property sold by father and family when he was Minor?

Dear Sir/Madam, I have queries regarding purchasing inherited land which was sold by a family with a minor son. One Mr. T was in possession of the 1 acre-11 guntas of land and sold it to Mr. S in 1965, Two years later he purchased it back from Mr. S through sale deed. Later on Mr. T and his wife and also his only son Mr. Ganesh died. RTC is transferred in the name of daughter in law 'Lakshmi' in the year 96-97. In Year 2009, 'Lakshmi' and his only son Naresh along with his son Madhu 19 years old and wife Chenamma representing minor son Shashi aged about 12 years, sold 20 guntas ( half acres) of the land to Mr. X and another half to Y, remaining to mr. Z. Now I am planning to buy 3 gunts(3267sft) from Mr. X. Does the minor son 'Shashi' have the rights to claim share in this property which is already sold? Can he challenge the sale of this property? He would have already crossed 21 years as on today,Since sale is 9 years old. I consulted a advocate in the locality. Initially he said Minor son can challenge it as 12 years have not passed after sale. But after further discussion, he advised me to go ahead and purchase as there is no risk. kindly request you clarify on the below queries. 1) Does Mr. Shashi have the rights to claim share in this property now? He would have already crossed 21 years as on today. 2) if he has, Can the sale to Mr.X become void or can Shashi only ask for partition to get his share? 3) What will be the share of Shashi, incase he has the rights to claim now?. Since his father is alive, I guess it would be 50% to grandmother lakshmi, remianing 50% further divided into father, elder son and Shashi. 4) If I buy part ( 3 guntas) from X, any chance this sale can become void, if Shashi demands his share ? Mr. X is keeping remaining land for himself