Not giving me feedback will ensure this game is never restarted, because I am all out of ideas.
Well, I don't really remember what is already in the game, but in term of plot point I have a fews ideas.
1- With the cuckquean plan in action, the daughter reveals her love for her father, but is stopped by her mother who doesn't respect her wish (because incest is wrong even with consent or something). With the truth out of the bag, the daughter decides to fuck her father behind her mother's back. First the daughter would have to convince her dad, maybe she tricks the mc into believing that the mother wants a more realistic NTR for her case, which works at first, by being a bit of force, but eventually has to revealing her lie to the mc as she realizes it won't last and believe that she got him hook. After, a lot of drama and fixing their relationship, they get back together. Later, they secretly get caught by the mother who is torn between stopping them or enjoyng her dream in a more "natural" setting.
2- For this one we would need to change the setting a bit from the current so accepting of the situation, because... for a teacher having an affaire with a student (and worker/coworker too) is a big no no, even more with multiple, but the wife is too horny and exited to think properly and let all of the school know that there is at leat a teacher in there actively looking to fuck staffs and students a like through the initial annoncement of the cuckquean plan. But happily, there is now way to know who is part of the plan, but now there are peaple actively tryng to find and end mc and wife carrer. Like, the director could be the principal antagonsite in this regard and giving out prime to find them and be like "you, exemplar student(potentialy blackmail by the director because authority figure over player throuth natural social order = always evil), get recruted in there harem and find who is being it and if there is more to it". So now we got a mole in the harem and she probably not even like the sex as she does it for justice and belive there is an entire organisation juste waiting to be uncover, but grow fond of mc and became a doubleagent for him.
Note : it's still work with idea 1 as hiding important stuff from your child is bad parenting, she is old enougth to know and turning your father in a wore use by most likely most of your contact is good to know.
3- Bref, a simple solution for idea that I see for this VN is to take a idea represented by a girl and try to avoid to reach a statue quo. If I remember correcly, it's a big problem in the current story. where character are not set up to have an arc. There is this girl wich is male averse in the story if I remember correcly. So she fuck the mc and then what? she is heal? No, make it that it's does'nt. Maybe she will never heal and most learn to accept it. Maybe, she try to throw the towel to soon and the mc take a more proactive role as her conrene teacher (and enventually lover). Maybe she is self destrutrice about it : she hate having sexe with the mc, it make her literaly sick, but she try and try again refusing to accepte that it will not work until she face her trauma or something (maybe she saw her mom getting rape or something). Oh! Maybe she become abusif with mc "raping" him like she saw her mother be or you know keeping with the self destruct idea and being the one "rape".
4- I saw a comment earlier sayng that all scenes must have a pupose or something like it. I must disagree. Sometime it is important to have a scene to relax or distract of the main story. You know... relax after a stresfull scene or being cool in order of being cool, or funny to be funny. If it fit and is not to much of a distraction, why not. It's all about the flow I say. Wich is why not all characters needs to be complexe. The ones just curious about the cuckquean scheme, a recurent but storyless partner, or student tryng to get favors could easily have one trait, be use as filler and background character as they don't realy receive the focus of the story once they have their introductory sex scene. Like "show don't tell" kind of thing.
Note: all the talk of characters not liking sex is volontary to contrast the protagonsits goal of sex for fun.
Bref, I am hopeful that my midnight rant help and good luck.