Yes, they did add standbys, including David and Jessica. I think more of the purpose is to try to get rid of the two-for-one standbys thing. Like Elisa, who plays cello, is the standby for Johanna and Beggar Woman. So if she went on for Beggar Woman, someone else would play the clarinet. But now they're having Jessica learn the clarinet, so she'd be able to sing and play the part. I can't say for sure that's what their goal is, but from what I know, it seems that way.
I suppose it's also good in case either the two characters one standby was supposed to cover are sick, or if the character and the standby are sick, the show can still go on.
But Em, your question confused me. Did you mean the above, like if 2 or sick, or just anyone? If you meant one, I think putting "understudies" in the thread confused you. Every substitute in Sweeney are standbys. They are all in the theatre for every performance. There's not one substitute who has another part, as an understudy would. So, does that clear it up?
And there's more difficulties in standing by these parts that meets the eye. Like who would "conduct" when Donna was out, the actor or instrumentalist (mostly the actor), etc.
"If there was a Mount Rushmore for Broadway scores, "West Side Story" would be front and center. It snaps, it crackles it pops! It surges with a roar, its energy and sheer life undiminished by the years" - NYPost reviewer Elisabeth Vincentelli
