While most overtures for musicals contain music from the various songs in the show (very occasionally also utilizing dance and incidental music), I wouldn't say it's necessary. In opera, there are overtures that do not include any music from the opera, perhaps most famously the overture to The Marriage of Figaro.
I would consider The Fantasticks and Threepenny Opera to have overtures even though they do not contain music from the score that follows, with the former admittedly being perhaps a bit iffy since it's meant to accompany stage action.
In a post above, I agree with you on not considering the "Carousel Waltz" to be on overture, along with several other pieces mentioned in this thread. |
