Alan Menken, whose Broadway adaptation of “The Little Mermaid” begins previews this weekend, talked about finding just the right song for Ursula the Seawitch to sing. Ursula is played by Sherie Rene Scott.

“We wrote three songs for that spot in the show. The third one finally stuck,� he says.

“The first one was called ‘Wasting Away’ and was written before Sherie was cast. It was based on the moment when Ursula says ‘I’m wasting away,’ and we see her gigantic, corpulent body sliding down.�

“It dealt a lot with her weight, very seductive, but very much with a physicality. It was a little bit of a one-joke thing and it was not really relevant with Sherie, although it would have been fine because wasting away was a metaphor.�

“The next song we wrote was ‘All Good Things Must End,’ which was so clever and so almost Cole Porterish. (Lyricist) Glenn (Slater) wrote a brilliant song. And it was really written for the end of the show, as Ursula is exacting her revenge, singing ‘all good things must end’ and singing, almost like ‘Tiptoe through the Tulips,’ delighting in their misfortune.�

“Introducing a new song at the end of the show was not entirely successful. We tried transplanting it to the top of the show. It stayed for a while, but we said we need to push the plot forward more in that scene, so it was out.�

Those changes came before the out-of-town tryout this summer in Denver.

The third song — the one they kept — is “I Want the Good Times Back� and it’s her story about how good it was when she was on top and how Triton caused her misfortune and she’s going to get back at him.

“You’d think it would be a plot song,� Menken says, “but Sherie turns it into this great performance tour de force and carries it to the back wall of the theater.

“I’ve heard people do justice to my songs before, but Sherie is quite an extraordinary performer.�