Uncle sold property of grandmother by deceiving mother and no consent

There is property of Nani. My nani expired in 1999. In 2006 a builder made an agreement with nani's brother for redevelopment. My mama got to know in 2011. My nani has 2 children. So my mama by deceiving my mother made a release deed and got her signature on that. I did not sign anywhere. No mama is delaying our claim and has sold the property to builder. It was undivided property. Now i got all the documents from the registrar's office. Now what cases can we file against mama and what are our rights in the property?