I think she should first understand the main plot and themes of the original manga. Then, she could come up with creative ways to make the story more engaging and appropriate for the target audience.
Well, for a start, she needs to carefully analyze the characters and their motivations in the original hentai manga. After that, she can think about how to tweak the storyline to make it more appealing and less controversial. Also, paying attention to the art style and presentation could enhance the re-write.
A model daughter re-writing hentai manga would have to be very cautious. She'd have to focus on maintaining the core elements while toning down any inappropriate content. Maybe she could add more depth to the characters or introduce new subplots to make it more interesting without going against moral standards.