I agree with what removing what you were making, but I do have an idea. You can do Tina's Sexual Mentoring like a Character completion (This is likely to be done way later, but I do somewhat like it though). Whenever you have Sex with a character (just once) or complete a route (like Debbie and Diane) it will increase a hidden condition and when you talk to Tina and have this condition high enough, she will do a "Mentoring Session" to help you (you can either do 1 or multiple sessions depending on character's seduced). These will be new scenes, but you could try to incorporate SPH scenes and stuff to it. By the end of the Mentoring Session(s), you will be able to make the girls unable to cum be able to cum (just changing the dialogue and no image changes and as an option to make them cum or not, if youre into that). Do you think this sounds good?
Also, another question, but about you workload with this project. How difficult is each aspect of your modding (finding the code, changing the code, changing the scene, what aspects of the scene is hard, dialogue change, adding new things to the code, new scenes, etc.)? And what takes up most of your time and what is the easiest thing to change or do?