To be honest I really do think the simple thing is true, Ayua is William and Miru's. But is Ocean brings infuta Helen, all bets are off. Ayua might not be the trans character, but the futa one, and that's why she's a special case.
Okay, that would be an outstandingly DUMB bit of script writing, but I posted the precedent, we can't pretend Ocean hasn't thought through these options!
Well, I'm thinking Ayua is Miru and William's child. But then you have the monogamists saying they won't touch Miru with a barge pole - they're team Katie (or someone else less interesting) all the way, so either way Ocean's getting screwed trying to make people happy. Maybe Ayua is the result of Ocean getting screwed by the LI fandoms? That also makes as much sense.
Also, we have to wait until WiaB or SG gets an update to find out who exactly is still a Zane and what that all means. Or Ocean's changed his mind again.