How can I not let legal heirs claim in joint property

I and my wife bought an under construction property in Banglore this financial year. I have added my grandmother's name to it. The reason being I had given amount to my grandmother few years earlier which she wanted to repay by selling another property. Also there was the long term capital gain tax quotient by the sold property. However I do not wish for any of the children of my grandmother (uncle n aunty) to claim ownership on the property in case of any unforseen circumstance happens to my grandmother. Want to understand what needs to be done so that I do not need to get NOC docs later