What makes you think that her power will go anywhere? If we can figure out how to take what doesn't belong out of her body - I mean, her body is the anchor for all of this, isn't it? Emily never had anything to latch on to and Ruby...she's been wearing that body for years. There's got to be a way to sort out which one belongs and which one doesn't.
...or at least which one is more familiar with that body than the other.