Settlement deed signed in family can it be cancelled

I'm venkat Hindu upara religion from chennai. My mother helped to built first and second floor of her father house who is retired railway employee. actually her father got loan from fund office in chennai by pledging his house document. My grandpa trickily used my mothers salary, pension of my late father, money of sold property of ours which we fought and got from my fathers brother through madras high court in 1990s, to give monthly interest and loan amount. After few arguments in 2012 my grandpa written a settlement deed and registered it without our knowledge. ( the settlement deed contains the house which is built with the help of my mother will guardian by my grandma after grandpa's death than after my grandma it will come to me and my sister by my mother as guardian). But today we checked EC through that we came to know that grandpa as cancelled the settlement deed without our knowledge. 1) It possible to cancel a registered settlement deed.