Switched at Birth (1991)

This is the story of the two babies who were switched at birth. A few years later when one of the girls gets sick, tests reveal that she was not the daughter of the couple who raised her. Eventually she dies. And the couple, most especially the mother, search for their real daughter. Eventually they suspect that it's a widower who has their child. While they try to find out if she is their daughter, the widower is advised by his attorney not to be so hasty to cooperate, because if she is their daughter, he might lose her, and she is all he has.