Both dramas have the same premise. The protagonists never met their fathers and have strained relationship with their mothers. Mysterious force sent them back to a time before their birth when they would meet their younger moms and become friends with them.
Both are about children going back in time to when their parents were young and understanding them better as people rather than parents.
back to 1989 is pretty good series with time travel theme.The ML is really smart and a good businessman but he has problem where he wants to find out who his father is,then one night he accidentally goes back in time when his mother was still young and close to the time where she got pregnant with him.......