Legal hairship in agriculture land.

Since last 25 years following are sequence of incident happened till now related to agricultural land : (1) my grandmother having land of 20 bigla after death of my grandfather in an accident. (2) my late uncle's wife decided to have their share of land and to part away from one joint family. (3) my grandmother had devided land in 2 parts 7-7 bigha on name of each of his two sons. (One on My father's name and other one is on my late uncle's wife name) and remaining 6 bigha my grandmother kept with her. During this excerice consent of my father's 3 sisters are taken in favour of waiving of their right on land. (4) now the following are present situation about the 6 bigla land my grandmother kept with her. My grandmother is still alive. (A) now my father's those 3 sisters (who have mutually waived their right on land approx 25 years before) have started to ask to add their name in agriculture land record with consent of my grandmother who lives with us. She being more the 100 years old will not have any say in either side and will not in position to refuse her daughter's demand. (2) presently land record is only having my grandmother's name.. my father's sisters told us that their name can be included anytime without any need of consent of their two late brothers legal heir wives (bhabhis) is it right? (3) Once waived their right on land about 25 years ago can they revive their right on land again With the consent of my grandmother? (4) What is the option to be exercise in order to prevent addition of their name in land record and subsequent share of land to them? (5) In case my father's sisters attempt to include only their name is it possible? Or (6) if yes than my late father and uncle''s legal heirs name will automatically included as per varsai aamba (certificate of successor/legal heir) as per talati record? Along with their names ? Desiring your quick advice