Unlike other TV musicals, The Little Mermaid Live! will play the film in the background

https://variety.com/2019/tv/features/the-little-mermaid-live-aulii-cravalho-john-stamos-shaggy-graham-phillips-new-score-understudies-1203392411/

Scenes from the original animated films will be shown on screen to keep the action of the story going as the crew sets up the next live musical number. “Everything that you love about the movie is still intact. We literally just burst off the screen to do these musical numbers,” says John Stamos, who plays Chef Louis. ALSO: The special will open with a special introduction from Jodi Benson, who voiced the Little Mermaid in the movie. https://tvline.com/2019/11/05/little-mermaid-live-changes-explained-new-songs-video/