I think it was a Christmas movie.
Basically I remember this guy and his wife had twins. One of the twins, the girl, had down syndrome, so he pays the nurse to take the baby girl away whilst they keep the healthy baby boy.
The nurse keeps the disabled child as her own, meets a trucker and gets married. The girl's biological father becomes obsessed with finding her, which he does. He's a photographer.
The brother becomes a singer, finding his sister when he is on tour.