Share in Ancestral property

This qs is on behalf of an Hindu old lady (O) who is 80 + yrs, regarding her share in self-earned property of her grandfather... this old lady (O) was married around 1940 s This is her history– and below are her words i am asking to experts My Grand father GF (1st to die around 1958 ) later Grand mother GM (2nd to die in 1959) had 1 ) daughter i.e. my aunt “ A ‘ [3rd to die in 1960] never married. & 2) son “ F “ i.e. my late father died in 1997 ,,, My mother (MO) died in 1979 . We are 3 siblings , 2 brothers [ B1 , B2 ] and me [O] Each brother has 2 sons.. [ S1 , S2 , S3,S4 ] My late father ‘F” had made a will that property should go to his four grandsons ( only brother’s sons) [ S1 , S2 ,S3,S4 ] We had consulted a HUF lawyer – he said the will is valid as you were married before 1956 and on death of your grand parents and aunt , property goes to your father (F) even thou you and your siblings were born . or if some dispute/ challange by you.. the maximum share you (O) may get is 1/8 th . if will is not valid and treated as ancestral property Property is still in my grandfather’s name .. Plz comment.