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If your grandfather had bequeathed the properties in the name of his grandson then even your father do not have any rights in the properties.
The beneficiaries of the Will, i.e., the three grandsons can arrange to acquire the properties by enforcing the Will left behind by your grandfather.
The beneficiaries of the Will can apply for grant of probate of Will even now.
an application for probate of will, cause of action accrues from the date when hindrance is put to legatee in the management of property bequeathed by will and not immediately after the death of propounder of will.
A will or testament is a legal document that expresses a person's (testator) wishes as to how their property (estate) is to be distributed after their death
under Article 137 of Limitation Act, the period of limitation is three years from the date and the said period begins to run when the right to apply accrues.
In a judgment by Supreme Court in Kunvarjeet Singh Khandpur v. Kirandeep Kaur, (2008) 8 SCC 463 it was held that an application for probate of will is for the court’s permission to perform a legal duty created by a will and is a continuous right which can be exercised any time after the death of deceased, as long as the right to do so survives.
Therefore the beneficiaries of the Will can seek probate of Will even at this stage to acquire the properties bequeathed in the Will.