Relinquishment deed regarding !

I have an immovable property situated in Jaipur. It is in the name of my deceased mother. My father also died and both left the property without any will. Me and my sister are the only legal heirs of this property. My sister is now a resident of U.S.A. .She wrote a Relinquishment Deed in my favor. The Jaipur Nagar Nigam ( falling under J.D.A) where the property docs and Death Certificates etc were submitted have now asked me to register the Relinquishment Deed to at the Registrar office whereas by now we have given Public Notice in the local news paper etc. The Nigam officials says that they can't validate the Deed unless it is signed / witnessed in the local Registrar's office . Some official have recommended me to call my sister down from U.S.A. to sign it before the registrar. Please offer your opinion in this regard.