The Idea of beeing able to sleep with your own (The MCs) children from Manaphy/younger Manaphies, is an interesting one that I could See you making into an interesting Mini-Game and a new interesting way to play the game and get some new images.
In total I don't really care about the fact that the new Manaphies are related to MC and OG-Manaphy, but this will make a good amount of people pissed of, but this can easily be prevented by making these scenes optional/adding a setting to disable them.