Transfer of undivided share between co-owners of joint property

Respected sir, namaskar. With your kind permission, the background of the matter is being elaborated hereunder - 1. An elderly person (above 70 years of age) has two issues - one son and one daughter. 2. Son is single. Daughter is married. 3. There are two self-acquired (not ancestral) properties - an apartment (elderly person, his wife and son reside there) and a shop (vacant). 4. Both of them are joint properties (undivided share) in name of elderly person and his son. 5. Because of age, the elderly person (father) wants to transfer his undivided share of these joint properties in name of his son to avoid any legal complications in future. So, queries are - 1. Can father gift his undivided share to his son (who is already a co-owner of these properties)? 2. Can son buy his father's undivided share of these properties in which he is already a co-owner? 3. Can a trust/estate/company be formed to attach these properties to it and then properties can be converted to shares and then father's shares can be transferred to his son? 4. In short, main purpose is to make son as sole owner of properties to avoid any hassles in future. So, from legal and taxation point of view, what can be the best and proper method to achieve sole ownership for his son? Good advice is highly appreciated. Thanks.