Spent ~₹40L on dad's house. Do I need legal ownership or is that morally wrong?

Wife and I spent ~₹40L renovating/building the first floor on my father’s property. Property is in his name and my parents live there in ground floor. We live in first floor. Recently a lawyer friend told us its best to protect our investment as a registered gift/settlement deed (father to son) of that particular floor.

Question is If we have a good family relationship, is a registered deed actually necessary? Asking him feels like I’m saying “I don’t trust you” and feels morally wrong or transactional. At the same time, if something happens to me or we have some family disagreements later, I worry about our position in a house we both helped pay for, but which legally isn’t ours.

Is there a way to secure this without making it feel like a business transaction? Genuinely looking for perspective