I'm starting to think the game should be called "Becca on my Balls," because the MC is a meek, weak, spineless pussy who is unable to stand up for himself, unable to be a decent father in any capacity, and 2/3 of the story is basically him capitulating and giving in to Becca's bullshit scheme.
Of every meaningful choice in the game, there is not a single one where you can tell Becca to stop.
Yeah. Incest/harem game. Get with all your daughters. I get it. Fuck, that's why I downloaded it and am playing it. But playing an insufferably weak piece of shit for an MC isn't fun. And when you are pulled into a sauna and witness one daughter mercilessly insult and berate the other, and ultimately blackmail her, so she strips for you, and you not only do nothing to stop it, but then just stammer like a 14 year old boy "I like your tits," you aren't proving you are someone they can trust or be close to. You're proving you are someone who is too weak to stop her from being exploited and humiliated, and then too lost in his own lust to do anything but stare at her in her most humiliating moment.
You wanted a chance to prove Becca's theory about "pecking order" has merit, or to prove to Lilith that you're a decent person with any level of self control and you actually care for her, you could make other options for that scene. Anywhere from you storming out of the sauna, telling Becca "you can't punish her based on the fact that I won't play your sick games," to having a full on confrontation where you tell the little whore that between her heartless manipulations and cruel tricks, down to resorting to blackmail to force her sister into a humiliatingly and compromising position, that you won't stand for it anymore. That you thought she was the one you were closest to, not just your daughter but also your best friend, and seeing her for who she really is, so soon after seeing her mother for what she really is, is more than you can take right now. And if you have to make the choice between playing her games, or standing up for Lilith, that it doesn't matter what Lilith's feelings for you are... what matters is that she is your daughter, and you won't stand there and watch her be abused, and that Becca has two choices: get on her knees, press her head to the ground, and beg Lilith to forgive her for the ongoing cruelty she has been inflicting... or to get her shit and leave, knowing she isn't welcome back. Because you're done with this shit.
Instead, what do you do? You let it all happen, then instead of being mad you listen to her bullshit explanation where she openly admits to "being her mother's daughter" (seriously, MC. Red flag. Stop being such a fucking pussy), and so a girl half your age, with her fucked up logic on how abusing her sister is a good thing, starts to get in your head because you're too busy thinking with your dick... to the point that when she pushes things further and jumps in the shower with you, you're too lost to put a stop to it.
I've had it with Becca's character to the point where I'd honestly prefer a path where you had the option to disown her and tell her that you want nothing to do with her anymore, and for your focus to go on Abby and Lilith alone. It shows some strength on the MC's part, and it shows that Becca's lies and manipulations will backfire on her as bad as they did for her mother, and it makes her pay for the horrible way she treats people, especially because, like a true sociopath, she has utterly no remorse, guilt, or care that she hurts other people.
A "reform Becca" or "abandon Becca" path would make the game much stronger, and make the MC at least appear to have some willpower and decency.