If I got it right, you said, your father got a property as a GPA holder. If this is right, then the GPA goes on death of your father.
2. Generally the relinquishment deeds would be registered in the registrr office which has jurisdiction over the property. So getting the deed registered in Mumbai needs to be checked first.
otherwise, what is said by my other friends hold good.
anantha krishna n.v. (Advocate AP High Court, Hyderabad, 9246531895)