First of all, I guess this episode is sitting in between of BB's narration. So at that point Kira is already a perv, Max fucked her, but his sister isn't that slut. Of course things will escalate pretty quickly, but I feel that things have to be more .. slow. Dunno, maybe she can try to put her aunt to bed more often during this episode? You're the one who's writing. Maybe the twist could be more elegant? Awesomeness is in the details.
This scene happens every Saturday. For the most part when writing these we are assuming you've gotten to the Harem ending of BB. You're anally fucking Lisa, you're doing camshows and threesomes with Alice and her girlfriend, you're fucking Ann, and of course, Kira.
Our next story, as has already been spoiled by the released CG is gonna be before max has had sex with Ann, but still at this point, you should have made it all the way with Alice, Kira, and Lisa, as well as gotten Alice's girlfriend in, and made Ann comfortable with non heteronormative sex.
I think you'd be right if we were writing this as the first time that this happened, before you've done anything with Alice. But the Alice who has joined you, kira, and your mother in the porn industry isn't the same Alice she was at the beginning of the game.