Yeah, it's pretty tough. That's the same thing going on with Doctor Amana: Sexual Therapist as well. Meepish is taking over art for RomanHume so the project can move forward. (Roman has been struggling to progress when continuing solo.) Meepish wants to use Gen5, but that means a lot of the models will change. She's really trying to make them as close as she can, but it's definitely not perfect and there will be changes.
IDK if it ever would be a thing, but if you can get stuff updated without completely redoing, it would be nice. I could see two possibilities. One, do like I mentioned: apply updated elements — more realistic skin, more nuanced and detailed eyes, etc. — to the older model. Or two, take a model from the newest Gen series or whatever and work hard on it to get it to look like the daughter (or at least incredibly close to her original appearance). The first is probably the least likely to be doable, but the second is the least likely to retain most of the appearance.