The manga is about the dead wife of the ML who reincarnated as a little girl. The man was touched by the appearance of his dead wife. And he had a daughter (or son?) who also later learned of the girl's reincarnation. One other thing I remember was that the girl had an abusive mother in her new life. So the manga probably has a tragedy tag as well. Anyone knows the title?
I dropped it early because it wasn't my thing so I don't know about the abusive mother, but maybe If My Wife Became an Elementary School Student
Could be it. The abusive mother appears halfway in the story and totally changed the mood of the manga.