"You Light Up My Life" written by Joseph Brooks, and originally recorded by Kasey Cisyk for the soundtrack album to the 1977 film of the same title, was lip synced in the film by its lead actress, Didi Conn. The best-known cover version of the song is a cover by Debby Boone, the daughter of singer Pat Boone.
https://en.wikipedia.org/wiki/You_Light_Up_My_Life_(song)
https://en.wikipedia.org/wiki/You_Light_Up_My_Life_(soundtrack)
https://en.wikipedia.org/wiki/Debby_Boone
https://en.wikipedia.org/wiki/Kvitka_Cisyk
https://en.wikipedia.org/wiki/You_Light_Up_My_Life_(song)
https://en.wikipedia.org/wiki/You_Light_Up_My_Life_(soundtrack)
https://en.wikipedia.org/wiki/Debby_Boone
https://en.wikipedia.org/wiki/Kvitka_Cisyk