Flat transfer to daughter

Dear Mr. Sethi, Need your advice on some queries related to a flat which is own my by parents in india and they are staying in Bahrain. We are 2 sisters and 1 brother. Both of us are settled. my brother is settled in Dubai with his family. but fast few years ne not been taking care of my parents they are 85 plus years. They keep calling him but he not responding or aking care of their day to day expenses. My father has decided not to give him the flat and to give it to we both daughters. The query is how do we go about the legal procedure for the same. At once they thought to sell the flat but he to has the keys and stays there when ever visiting india and as his stuff belongings also in the house. The WILL for the same has been made in own name but legally he is worried his son might challenge the same in court and not let us on the property and get it to litigation. they stay in tht flat when in india but from past few years have not even bothered to pay the maintenance and other society charges. My father is been paying the same. Can you please advise how to go about the same. Thanks