Deed of settlement

Deed of settlement: My uncle's father made a deed of settlement for a open land of 100 cents. Recently my uncle died and his father cancelled the settlement and registered to his 3 daughters of 32 cents and providing remaining share to my uncles wife n son n daughter. In deed of settlement he clearly mentioned that at anytime or any means the settlement wont be cancelled. My question is will the deed of settlement will be cancelled even after the death of my uncle ? Or how we can handle this ? Or will a notice/case will help out ? Or whether a share will go to uncles mother/father ? Please advice. Thanks in advance.