I don't think SE would lie on us, as much as that statement sounds odd, I wouldn't think Lumina is Serah. Not *directly* anyway.

I do wonder what sort of tricks and annoyances she will be doing. Is she just a little nuisance, getting herself in trouble and therefore having Lightning save her (Which might even lose her overall time? Who knows), or a more serious threat.

I'm very intrigued as to how her character plays out.