Document movable gifts taken in last few years

My father has gifted me money over last few years after my marriage by way of creating fixed deposit in banks in my name, deposit in my PPf account etc by cheque. I too have been paying income tax on income earned out of those. Seeing the bad attitude of my brother towards my father & avoiding any future conflict, someone has suggested to my father to make a documentary proof of those monitory gifts. Please suggest if it is possible to execute a document now by my father in my favor for money transfer over last 10-15 years? What type of document it should be? Will it be a strong proof that can't be challenged latter?