Age regression

I’ve found a idea that I would love to do based on a hentai I saw, where a character somehow just much younger. 
 

Ideas for include-

Mom and son-Mom gets younger and finds her son attracted to her. Or the son is older and goes back to a young boy and the mom finds his cuteness irresistible.

Dad and Daughter-The father is getting older and has a teenage daughter who his is attracted to. And one day he finds hisself his daughters age.

Older brother and younger sister- The two new stepsisters hate their older geek of a brother but the brother finds himself young again and the sisters think he is a cute neighbor boy and adore him.

HeadMaster’s Younger Brother and a private all girl academy-It takes place in a private all girls academy and my character is the younger brother of the HeadMaster and the only guy there. The girls don’t like him and shun him, but one night my character finds himself a young boy again(Expect for his cock size). The girls find him adorable and think he is a kid brother of someone on the campus. My character finds himself in some sexy positions after that.
If you are interested in this, let me know.