Property issue between me and my father younger sister

Hi, This is not a ancestral property which I am telling you about, self earned property by my grandmother(dads mother). May be 5yrs back my grandmother shared the 15 acres between her, my dad and dads sister, 5 acres each. My grandmother wrote a will stating that till my sister gets married the property which she wrote for dads sister name, it will be in her name and while my sister getting married we can make use dads sister property. We did use the property of 2.30 acres for my sisters marriage, we sold the property and took the money for marriage purpose. remaining is still in my dads sister name . As per will it should have been transferred to my dad if he is live else me, but she did not do it. *Can I ask the transfer of property now to my name. *Whether I have a right on that property now. *But the will my grandmother wrote is not with me, but now also my grandmother says get the property transferred to my name. *May be the will is with the lawyer where we done the agreement. *Whether my dads sister has rights on self earned property apart from 2.70 acres that is in her name, can she claim for the remaining property that is there almost 10 acres. *I do not have parents, deceased, I am just now getting transfer the property that is there in my grandmothers and dads name to my name. *Whether it is compulsory to have a will that my grandmother wrote to claim the property that is there in dads sister name. Please give me the solution, what we can do in this situation. Thanks & Regards Roshan B