Relinquishment of property land in Visakhapatnam

Dear Sir, I am an Nri enquiring about drafting of document regarding relinquishment of land and property in Vizag, India. We have 1 land and 1 flat in Vizag which my late father left behind on his name when he died in 2015. Is it possible to make a signed relinquishment document from a mother - signed by her and I bring that document with me to India or give a Poa to my aunt in India to act on our behalf regarding this issue. My mother is also not well - she has schizophrenia - paranoid as she speaks to herself. I have a signed letter from the big hospital here in Preston, Lancashire. I have asked her to sign a Poa but I was wondering if this letter would be enough to act of her behalf as a reason for her not to sign. Her behaviour is paranoid and unpredictable. Can this letter act as a reason for her not to sign relinquishment of her one fifth part of my dad's estate to myself and my 4 siblings. Also in the event of her not signing after her final expiration is it still possible to go ahead with registration of the full estate under our 4 siblings names. My email address is [deleted] .