Rights of my sisters on ancestral property

There is an ancestral property of my grand father and grandmother and uncle. They are 3 purchasers of this flat in 1985. Now my grandfather had 4 children. 3 sons and 1 daughter 1 son was adopted by another family and his surname was changed. All 3 sons got married and they have 2 children each. Elder son has, one daughter one son Middle son has two daughters Younger son has one daughter one son. Now in 1992 grandmother died with no will. Grandfather died in 1994 with a will but unregistered only notarized mention his share to elder son. Middle son died in 2001 Younger son died in 2010 Elder son died in 2018 Elder son before died filed a probate in 2004 which was objected by middle son and his wife which is still in court. Now I am eldest male member with one real sister and two cousin sister. Will the 2005 act of daughter will not get share if father dies before 2005 apply. This question is for the middle son who died in 2001. Now we are doing partition so want to know who all are legal Copaseners.