zoran912, Saycon Sengbloh has been with the show since the initial concert in 2007. She sings "Abie Baby" and is one of the trio who sings "White Boys," among other things.
Though she could replace Patina Miller as Dionne (she went on for the role for two nights when Miller was ill during the run in Central Park,) she'll be in the Broadway company regardless.
In regards to Sheila, the rumors about Julie Reiber being cast seem to have died down. Most recently, I've been hearing that Alisan Porter (who originated the role of Bebe in the A CHORUS LINE revival) may be Caren Lyn Manuel's replacement.
Tonya Pinkins: Then we had a "Lot's Wife" last June that was my personal favorite. I'm still trying to get them to let me sing it at some performance where we get to sing an excerpt that's gone.
Tony Kushner: You can sing it at my funeral.