cancellation of settlement deed

property and all corporation tax are all in my grand father name. i have two brothets totally 3 members ...my 1st brosther had cheated my mom me and 2nd brother and made registered dhanasettle in 2008. by 2015 feb month i found and cancelld the settlememt by my mom and witness as me and my 2nd son. whether the settlement will be cancelled . because it is an undivided property.