I don't think Maddison is not mature enough to consent to stuff, but she's also not (yet) interested, thus I am less interested in her than Olivia (who is frankly impossible to resist). That will probably change later, hopefully they do it well but it's going to be a bit unbelievable I think.
It's going to have to be done well, and with sensitivity. I don't really have any basis to agree or disagree with the assertion that Madison's emotionally/sexually prepared for a sexual relationship with her father — two of the three things Allison isn't — but if she's not emotionally/mentally ready to even
have a relationship with him, she's either going to act out impulsively and destructively, or have to work through the latter issues before she can possibly deal with the former. If she's next, it's going to happen quickly and mostly out of nowhere. If she's third, they actually have time to build some sort of foundation. Whereas Allison, as written, can't possibly know what she's getting herself into, and unless Olivia can 1) get over her hostility to the idea; and 2) gently walk her through what she's about to do, and the potential consequences thereof, it's still going to feel icky. If they were all in school and there was some sort of sex ed class, it'd make this a lot easier. But I don't get the sense that
Radiant intends to extend into a school year.
(My headcanon regarding the girls' naïveté is that their mom only only had the time/health to talk to Olivia about sex and relationships; after that, she was too sick. Which is why only Olivia seems to have any idea what she's doing, why she probably shouldn't, and why she wants to do it anyway. Which is another "the girls are actually way younger than the player can make them" argument, and one I prefer not to think about.)
As with Allison, I feel like Madison's X years old in the writing — the perpetual tantrum, acting out for attention, doing things even she knows are wrong because she doesn't know how else to act — and that age isn't one I'm able to accept in my playthrough, nor is it one Patreon or F95 could accept, so there's a disconnect between how I'm able to view her behavior and how the devs view her behavior. But that's speculation, of course.
I'm just grateful they didn't render the daughters as young as I suspect the devs intend them to be. A lot of games where the fetish isn't the incest taboo so much as it's age play, as I think is the case here, regularly test the loli threshold. I can't play most of those games (nor shotas, either). Even then, I struggle with Alita, a lot. By way of comparison, I eventually managed to finish all the routes in
Parental Love, but Ada made me profoundly uncomfortable every single time. I don't even remember if she was assigned an age in that game or not, but she was very clearly quite young.