Why does Amber Von Tussle sing "Mamma I'm a Big Girl Now" on the Broadway production of Hairspray?

Question

I've seen the movie but I have yet seen the production;; I was wondering why she was singing about an audition when her mom was the producer and she was already a dancer?? Or is it completely different in the show?

Answer 1

Amber didn't sing the song, Tracy did, and the reason tracy did sing the song was becauseTracy's mom was against her dreams and thought that people wont like tracy or her mom because they were fat.  

Answer 2

Tracey Turnblad sings that song.