A time-traveling book; a child changes their parent’s childhood, for the better?

Hi, is there a book about a person who goes back in time to help their parents when they were also children? For example, their parents might had a tough childhood, so you go back in time, maybe not to fix their problems but give them a shoulder when they might not have it at that time.

I realize this sounds really specific but this idea just stuck to me! Would be cool if a book like this exists.