Care to elaborate?
From what I gather, the dads switched right after the family arrived in town.
When you go to the sexworld in there you find "real dad". SW-mom explains the fact that they have switched.
Do they ever mention that they switched back to normal? The "sexworld dad" probably doesn't know that the MC went to the sexworld in the first place and he's just playing it off.
Same goes for the sister's story, what gave you the impression that the dad's switched back when he came back to apologize? Again, maybe he's just playing it cool to not raise suspicion.
From what I can gather, the reason that Vi lured the MC to the portal in the park was because the sexworld MC crossed over to hide so he doesn't get sacrificed.
I kinda get your point tho. All these stories seem a bit self contained, like they don't have any effect on eachother, or barely any.
Also there's this interaction where if you went into the sexworld before doing allaway's story, this dialogue happens.
That dialogue is weird anyways... What, so SW-MC tried to mirror everything we did on the sexworld, then why was everyone worried that the MC disappeared?