Ok, since this has been driving me nuts for about twenty years, I'm posting this suddenly:
The vague idea I had here was that the twins were NEVER meant to be Kurama's children.
Their mother believed he was, however, this was because their father tricked her by pretending (shapeshifting) and on her deathbed they declared revenge for what they thought was his mistreatment of her. This was going to bring me to a new bad guys for our heroes to fight, as well as make the twins new team members to help round out my pairings. Please don't ask for me to update this, it's just really bothered me where the story left off and I needed to have some kind of conclusion.
Thank you for reading this. 3 All the Love.
Aqua