Proof of acceptance of Gift Deed without taking possession

Hi, I currently jointly live in Flat owned by my parents (Flat is in name of my Father & Mother) bought by them and is not ancestral property. Currently 7 members stay in the flat which includes Father, Mother, Younger Brother, Younger brother's wife, my wife, my daughter(minor) and myself its 2BHK Flat. Recently there were quarrels and dispute between me & my younger brother due to which Mom & Dad has suggested me to stay separately and vacate the room in which my family stay to avoid further quarrel. Reason for choosing me was that I earn good and can manage alone but younger brother's earning is not that much to afford taking new or rented flat on his own. I have a concern that after I vacate the place and later after dismissal of my parents there are probability that my brother will have complete possession of property and later he will not will to sell or give my 50% share in property. My parents are ready to create Will for equal share in property of both me and younger brother but after consulting friends and going through various articles on net Will is not safe option as that can be changed anytime in lifetime and my brother can misuse them for taking complete ownership of flat as me not staying there will not come to know. Many have suggested to go for Registered Gift Deed by which parents can transfer their 50% rights to me and it will safeguard my interest. As per articles and information I collected on Gift Deed it says Donee has to accept the Gift in the life span of Donar for Gift Deeds to be valid or else its not valid. Acceptance of Gift can be done by taking possession of property. In my case if I go for Gift Deed how can I proof my acceptance of Gift legally without actually moving into the Flat as I will be leaving separately and my Parents, Brother and his wife will be staying in it. Need guidance what will be the best option for me to safeguard interest of mine and my dependent later in case anythings happens to me later to fight for the rights and share in property after parents. Currently we don't want to sell the property as they have emotional attachment to it. Please help with the best option for me