Board Thread:Spoilers!/@comment-4877635-20160722094328/@comment-24674051-20161003164917

Indeed, Jabber specifically said Stepsister.

And after seeing the promo last night, It's hard to tell who is portraying the Lady Tremaine. We'll likely know soon enough once they release the press release (ususally done on Monday's). Though the casting would not be conclusive, in and of itself.

However, I'm guessing that the Lady Tremaine and her 2 (remaining) daughters made the trip to the LoUS for some presently unknown reason, but when the arrive in SB, they immediately look to destroying Ella's happiness. Which is where Emma is likely going to end up stepping in, since Ella is the first happy ending that she restored after coming to SB.