Hello!
Distribution of property among Hindus can be in two ways. One is testamentary where the person leaves a will before he dies and the other is where he dies intestate which means the death of the person without any will.
If the deceased person has left a will stating the distribution of the property after his death, in such cases the will of the person is followed and distribution of property is done accordingly. In the second case, the property is divided among the heirs of the deceased person according to Hindu Succession Act, 1956.
In your query you have mentioned that your father left a will before passing away mentioning the beneficiaries, then the property will be divided according to his will. According to his will, the property will be received by your mother and the elder sister has no say in the distribution of property.
Best Regards,
Vasundhara Singh
Law Student