Mr. Mu
First of all, congratulations on your proactive approach in tackling this difficult task. I wish you the best of luck and good work, whatever your approach and interpretation (whether you consider something or not) of what I will recommend next.
If you are really thinking about remaking the game (I believe this is the best alternative; I don't think continuing from where the story left off is a smart choice), I have some recommendations that I believe are a good way to approach the game and will help you finish it.
1- Feedback: I think the most important thing before anything else is to remind you that (if you've taken on this challenge) the game is yours. Every decision you make in the game's production must take into account what YOU like, what YOU prefer. If you are doing something you enjoy, having fun, and looking forward to the next stage, it feels less like work, but don't forget that it will still be work. There will be days when you won't even want to look at the computer screen or the daz3d interface, so it's important that most days you enjoy what you're producing. In other words, many people will give opinions on the game, and I'm sure you'll often consider them, but don't let that dictate how you make the game. It's yours; who are we to say how the game should be made?
You can even ignore what I'm about to say, because it's your game, isn't it? But I recommend reading it.
2- Models: I think the character models should follow your interpretation of what the previous developer had done, maintaining the essence but adding your own touch. Exactly as you've already done (btw, I really liked the models you already made; they turned out great).
3- Complexity: I believe it's bad if you start by adding too many characters or creating free-roam mechanics, minigames, and/or to-do lists; it will only delay the game's development, make the code more difficult, and hinder the implementation of new content. I think it would be good to keep the mechanics linear, with simple choices for now. Also, it would be good to have few characters at first; I recommend closing the main family's storyline completely before introducing a new one. This will help keep the development fast-paced, and each update (however simple) will advance the story, instead of stagnating for too long with a particular character.
4- Plot and Sexual Tension: But how would I keep players interested without new things? (new characters). It's simple, your game has to stand out for its sexual tension, and since the game's premise is to corrupt an entire family, it would be interesting to address the evolution of their corruption step by step. Start simple, just like in the original game, introduce the characters and their individual problems. The MC offers help to solve everyone's problems, so have the MC "innocently" touch the victims' bodies, one at a time in isolation, and gradually escalate these actions: "This dark hallway in the house seems interesting for teaching Hailey about carrots"; "This bathroom seems interesting for teaching Riley how to act like a man." Then start touching them in front of the others, but do it discreetly: finger Alice from behind in front of Oliver and make her act as if nothing is happening; stimulate Hailey's anus while talking to her mother; throatfuck Riley under the kitchen counter while making a sandwich and talking to everyone in the house. Then start revealing it to the others little by little, very carefully, when you are sure it's not a misstep, until everyone in the house is under your spell.
Furthermore, these are just recommendations; this is how I would approach this game if I had the time and patience. Whether you consider them or not, good luck with the development, and congratulations again!