Joint property ownership dispute

Hello : My name is Pankaj Parikh I am 76 year old and living in USA since 1979. I have property with my older brother ( Sunil Parikh) in Santacruz west as 50% property owner since 1978. I have original property document that shows our partnership since than. This property was listed for redevelopment since 2013 but nothing happened due to several reasons. After waiting for so many years living in USA I do not want to involve in redevelopment process therefore I repeatedly asked my nephew Kartik Parikh to sale it and give me my share of 50% but he does not want to move from this area. I am still paying my due for maintenance since 1978 as partner. I visited India in March of 2019 and ask my nephew that I want to sale this flat since I am getting old and like to close all my business in India. My nephew Kartik Parikh showed me new revised property document that shows his Mother ( Kunjbala Sunil Parikh) as sole property owner since my older brother died in 2004 and they removed my name as co-owner of property. My nephew Kartik Parikh listed as first 50% nominee and my name Pankaj Parikh listed as 2nd 50% nominee after Kunjbala's death. I was not aware of this changes and I never gave authorization to remove my name as 50% OWNER OF PROPERTY. I talked to Kartik that this is forgery and I would like to revise the property ownership as the original document as myself and bhabhi as joint partners. He said there is nothing can be done. Than I said sale it or gave me 50% of appraised value and you can be sole owner. He said he does not have money. My younger brother in law is trying to make him understand about the consequences he is facing. We just gave him one month time to answer our request by end of july other wise we have no choice to go through legal action. Since I live in USA and not aware of the Indian law system. I would appreciate your suggestion and any help you may provide to me. Thank you Pankaj parikh