No!
William + Miru = MC
Leia + William = Summer
William + Daphne = Nami
Why would Willi and Miru hide Nika, when they declare Ayua a Zane? Also, Summer wouldn't even be in the situation unsupervised dating Nika while Willi and Leia thought Nika was trash, and Elsa's mum (who would be Leia's other sister???) making comments about Summer ending up fat drinking beer in a trailer park also reject these two ideas. We gotta remember that SUmmer and Nika were dating and hanging out in the way teeanagers do with, the parents knowing where Summer was when she visited Nami, and for long enough for the parents to call Nika trash while not doing anything. If Willi was both their dads, it'd be over in a heart beat, Summer would disappear before it was a thing, game over.
Elsa's mum being Summer's mum's sister means that she is none of the characters we know from WiaB yet. The only sisters we know are Zane's in WiaB. Elsa is not Katie's daughter. Elsa's surname (seeing she's not married) suggests no tie to the Zanes - most logical assumption is Summer's mum is someone currently unknown.
Willi and Miru do want to breed, and Ocean gives us plenty of opportunities so far. Having said that, Ayua is in the same classes as Nika and Nami, so likely the same age, unless like Nami, she's been held back a year. Miru can't have two children a couple of months apart, Nika would need to be at least 9 months older or younger, and that only if Miru is such a sex fiend (well, true) and WIlli shoots and scores every time (hence basketball genes). But it still makes it pretty implausible for Miru to be Nika's mom, on top of the fact that AYua is raised as a Zane and Nika isn't.
Last one? I see no issue why not. Do we know if Daphne's last name is Cyrus? The only connection between Nami and the Zane's is the earring though. It wasn't left by Leia at the hospital when Nami was born, but seemingly by chance, when Nami was along on a random day out. I still favour the idea that the Zanes are responsible for Nika and Nami being orphans and the earring is a mark to show they're under Zane protection. It could just as plausibly be Nika = Daphne+Willi, Nami = Daphne + Mr Cyrus.
Given the ages, none of the sproglings are a result of creampies that occur in WiaB's game, if WiaB occurs 20 years before.
Also, unless a bunch had gap years, Nami is the oldest in the class.
See this is the ral problem, 'uncle' Willi taught him basketball, but not what balls are for. I mean in WiaB Willi was going to play wingman for Lucas, maybe in SG we'll have one hell of a funny scene where he tries to play wingman for Nika, making up for lost bonding time?
He being a son of incest counts? I think it needs to be in the game, not a consequense of acts before the game.
Would you risk that in his place, seeing that they change the rules to target new things they dislike? For Ocean, the story is the important thing, and so far I don't see Nika's parents being Willi and Leia as a immovable plot point. Willi most likely from a cheating episode (hence WiaB's NTR) with someone whose surname was Cyrus, who already had a husband, and had just had a child (Nami being a year older than Nika).
The actual defined family ties are currently less important to the plot than:
- Nika's depression/trauma
- Nami's weird hidden behaviour in the past
- Summer's disappearance
- The Bella/Stefan plot
- Moving to the Benz's
- MOving into a shared student dorm.
Currently, you can imagine anyone as Nika's parents and the current plot has maybe one scene that would change - Katie meeting him at the book club. Even that's not a given as Katie is the person driving the basketball plot from behind the scenes, and Nika's the star basketball player the coaches knew about for years fom a potential feeder school.
The real reason we imagine who Nika's parents are without the evidence is the sense of synegry we feel, and standard plot devices. But regardless of what we all think is most likely, almost none of the game currently hinges on it.