Can sisters claim elder brother's share after his death?

It is a self-acquired property of the father, who has two sons and three married daughters. The elder son is unmarried, and the younger son is married. The father wrote a registered will, stating that his wife can sell the property. If not sold, the property will be shared between his two sons, and the daughters will not have any right, only receiving one lakh rupees each. Six months ago, the elder son died, and the mother recently passed away. After the elder son's death, his three sisters obtained a legal heir certificate for his share. The younger brother refuses to share the property value and insists on giving only one lakh rupees as stated in the will. The property has not been sold yet, and he plans to keep the property for his own use. Can the sisters claim the share of the elder brother who died six months ago? What should they do to claim their share?