Father Is a Bachelor (1950)

William Holden plays a drifter who comes to a small town and discovers a cabin in the forest where five kids: January, February, March, April and May are living without parents. Their parents died a while ago, and they want to keep that a secret from the townspeople, especially the young school teacher (Coleen Gray) because they don't want to end up in a children's home and then eventually separated. William's character moves in with the kids and poses as their uncle to take care of them while romancing the school teacher. In order to keep the children, however, he has to get married.