Testament

Hi Sir, Humble request for a suggestion. My Great grandfather owned a property which is still registered in his name. My grandmother with her brothers and sisters all agreed to let the property to be used between 3 or 4 siblings, where few who were well settled did not claim any share. Now all the siblings of my grandmom passed away except my grandmom. and they did not give any share to my grandmom. their son's daughters have built house in the property and did not give any share. My grandmom is 98 yrs now. she has an unmarried daughter (my mom's elder sister) and we wanted to get share and give it to my aunty who can use the property. can anything be done. many times our family members agreed to give a share but they dint take any step and we being a family did not take any legal step, but to help my aunty who will seperate after grandmom passes away, we thought to do the needfull. Kindly share a suggestion.