Haha, thank you, Kad. I think Murphy is going to be wonderful as the Witch, anyone who saw her in FOLLIES can see how she'll easily pull off the glamorous part of the role, she'll be regal and fantastic, I can't wait to hear her rendition of "Last Midnight," I imagine it'll be nothing short of mind-blowing.
I believe Peters' involvement came very late in the game, not too long before rehearsals started, and there's some really cool old threads about this that get into how Peters got involved (and it's also talked about in Secrest's Sondheim bio I believe), but I do remember that it was agreed upon that Peters did this almost as a favor to Sondheim when they were scrambling to sign up someone for the role.
"Some people can thrive and bloom living life in a living room, that's perfect for some people of one hundred and five. But I at least gotta try, when I think of all the sights that I gotta see, all the places I gotta play, all the things that I gotta be at"