Can Relinquishment deed be cancelled

My father and his sisters has relinquished the property in favor of of his younger brother.So,that mutation of property can be done.As in the deed it is written that my grandfather does not have a will.But made a will and gave the authority to sign on the papers of the property to my father's younger brother.But the will is not registered. However, my grandmother is still alive.Her will has also been created which is registered.In which it is written that the percentage that has been provided by her husband in its will shall be distributed to all her children equally. Can the will be cancelled or it is null/void.