Is there a way you could do a find and replace with "Step-" whatever, via a toggle switch? I know nothing about coding, so maybe it's much more complicated than that. Either way, thanks for the response.
You could technically do that, but the game is explicitly written that the characters are blood-related, if you just blindly shoved a "step" in the appropriate places it would be very obvious and wouldn't really work or make sense with how characters refer to each other. It would basically require rewriting anytime the family talks to each other or when other characters talk about them.
And not only that, one of the main cruxes of the plot is the MC trying to slowly condition his family to be cool with him fucking his sister, as well him coming to terms with it himself, which wouldn't believably be as big of a deal if they weren't related. Like, obviously still questionable, but not possibly relationship ruining.
Plus, I don't think it would be presumptuous to assume we should expect some level of content of the female family members interacting sexually with each other in the future (beyond what's already there). And if they're already you're step mom and sisters, then there ain't no way to make that kosher.
Basically, it could be done, but it would be so intensive as to probably not be worth it for the dev to consider while the game is still in active development. Maybe someone could make a custom mod for it, but I don't think I've ever seem someone mod the incest
out of a game before.