Mr.Sankaran has not given the vital information as to whether the property belonged to minor or absolute property of his sister.
If the property was owned by his sister, she herself can file a suit challenging the sale.
If the property was owned by both his sister and her daughter then, both can join together to file suit.
If the property was of minor, the mionr daughter can file suit within 3 years of her attaining majority.
Mr.Anish Goyal is correct.