Can a mother transfer ownership of the house to the younger son without the consent of the elder?

I had applied for a MHADA flat in Mumbai on my retired mother's name since I didn't qualify based on my income. The scheme was for Lower income group(LIG). My mother fits into this category. Fortunately, we won a house in the lottery, but it can only be purchased under my mother's name due to a 5-year lock-in period. After that, the property can be transferred to my name. I'll fund the house purchase; it'll be in my mother's name, bought with my money. She'll transfer it to me after the lock-in period. I also have a younger brother. He has no objection with above arrangement as he is not paying for this house. However, we never know how one would behave after 5 years. Thus, I want to understand what can be done legally in advance to facilitate this transfer of property in my name without any complications after 5 years? Can "Registered will" help? Or/and "Power of attorney" will be required? Kindly advise the best legal solution for above mentioned issue.