Adopted childs right on property

Dear sir my G.father didnt have children of his own so he adopted a boy from 1 brother and girl from other. My mother was a 3 month old baby at the time of adoption...her secondary school certificate show's My G.father name at D/o....my G.Father has a House which was is own purchase and land which was inherited...My G.mother got the house registered in her g.son's(from adopted son) name at the time when my mother was small girl...land was in joint family till last 2years because there was a family run school in that place...my G.father, G.mother, their Adopted son are not alive...we have come to know that g.children(from adopted son)have transfer the property on their name without the knowledge of my mother. Q1.Will my Mother have the right on this property both Land & House? Q2.What additional proof will my mother need to prove the adoption other than Secondary school certificate? Q2.Will my Mother be eligible for a share in the property of natural father?