Query on Succession act

My grandfather has 3 sons and 2 daughters. all 3 sons are married and 1 daughter is married. My grandfather owns a 4000 sq ft land (long lease for 999 years) and also a house (tenancy basis). Before my grand father passed away in 1993, he gave all his property (moveable & immoveable) in name of his unmarried daughter. all of his remaining children had given a NOC to the effect. Now the unmarried daughter is the owner of all the property basis the Will of my grand father. None of the property is self acquired by the unmarried daughter My question is a) What happens if the unmarried daughter dies without a WILL? b) Who will be the legal heir of the unmarried daughter after her death? c) Can the other married daguhter/her husband or son claim right in the property while the unmarried daughter is alive? d) Can the other married Daughter/her husband or son claim right in the property while the unmarried daughter dies without will e) can the wives of the married 3 brothers or their children claim the property as their husbands have already given NOC? however this NOC is just on a stamp paper and not registered or notarised. f) Can the long lease property/land be sold off? What do i need to check to sell off the property? I would be grateful if my above queries could be answered