I have a couple of theories on the subject. 1) The Daughter is not a person yet a part of the court of the ruling body of Seanchan. like say the empress rules the Court of the 9 moons, the daughter of the 9 moons will be a lesser ruling body. And as to Marriage I belive that the "marrage" is Mat commitment to the ruling body. I mean come on, do you think that the proffecy would be that simple to figure out? I mean we have Perrin with the hawk and Falcon, you don't know the Hawk is Berlain untill you realize that she is repesented by the standard of her citystate. 2) She is the Daughter of the Empress. I also belive that Mat might go to Seanchan, maybe RJ lied to trick a bunch of nieve saps? One last thing, when Mat Say that thing of the Daughter of the Nine Moons taking him, and that one dude hears him, maybe he tells the Daughter and the invasion is just so she can meet Mat for one comment he said, It sounds like the Pattern moving in messed up ways, dont it?Its easy.