Kieri's the kind to, when she upgrades to a room of her own, miss bunking beds and go back to how it was before. That also includes eggs laid by her darling husband.

Sharing an egg isn't incest, it's what twins do. Especially in situations where unbirthing and cum melting is used as a way to unwind. But Kazai's gonna take some convincing.

Don't ask me how the size works. I'm not into micro/macro, so feel free to fill in the blanks I deliberately leave, with whatever you feel.