I can see that plot development making a lot of sense, since we've come to care about Ros, the outcome of that casting change would have a lot of impact. As it stands, she seems to be subject to increasing abuse by those around her. But in that case, she'd need to have some reason to remain loyal to the other party in question.
Actually, now that I think of it, they may have Ros be the substitute for Chataya... though, I can't see how they can use Daisy in place of Alayaya.