The son has a chance if the father dies without a will, then the father’s assets will be divided among him and his sister as per hindu succession act
But if there is a will the son can contest it —
—though the son will have to prove the same
Common reasons to contest a will include
lack of testamentary capacity (the person wasn’t mentally capable to make the will),
undue influence [someone pressured the testator (the father)],
or improper execution (the will wasnโt signed or witnessed correctly)