Grand mother's property issue

We all four grand daughters and all four are got married. My grand mother is having a commercial property. she is having only one daughter (1) and the daughter (1) having four daughters (including me). my mother and grandmother don't have any son's. Before dying, my grand mother has made a veelunama that "the property belongs to her daughter (1) and after her expiry the property belongs to her four grand daughter's". As per my grand mother's wish, when she was alive, we all four daughters planned to construct a house. which will be divided into five parts and one part will go to my mother. after my grand mother's expiry. we started the construction. Now my mother and my father simply delayed in registering the property individually to get individual loans. meanwhile they got the plan approval for the house with my mother's name, and we all grand daughters invested for basement of the house. now my father and mother is asking to invest money to construct house with their name. and they are blackmailing that they will sell the property. and my father is having one more family and he is having three son's. can grand daughter has any right on the land in selling the land.