I don't know what the big flip is about Rhiannon's voice not being amazing. I see the same people, who love Nicole Parker in Wicked for all of her "acting" over her singing, judging Rhiannon for having a not so strong voice. Ha. Yeah, anyway.
I'm pretty sure Alex is still Margot, so I think Rhiannon is being put back in as one of the Elle covers. Laura and Lauren will alternate it, but Rhiannon is now the "first u/s"
Rhiannon is still out until St. Louis, and she won't be able to be THE Elle considering her stamina will probably be low from being off of tour for over a month, she would only be good for a few performances until she got back into the swing of things.