Issue on rights to ancestral property

We had a house of our grandmother, who wanted it to be divided equally in the name of her 5 sons. Before the death of the grandmother, a will was made in the name of eldest son who was supposed to carry out her wish of division of the property. Unfortunately the eldest son died in 2003 leaving his kins( a son and a daughter) the legal heir of the property. In March 2009 the younger son of my grandmother by convincing got a decree done in front of judicial magistrate in court along with the kins of eldest son making them say that they are ok to transfer the property in his name. Now in 2019 the younger son has died leaving behind no will but his wife and his son as his legal heirs. The wife and son now choose not to honour the wish of the grandmother and are refusing the right to be given to any of the survivors of the kins of my grandmother. What all legal options are available in this case? Is there any hope that justice shall be done. Please note that there's no written document stating that my grandmother wanted to get this property equally divided amongst her 5 kins. Please help