Hey, thanks a lot for the kind words - high praise indeed! I really appreciate it :)
As for the kids, you need to meet a certain character first. This character has two requirements: First, you need to have met and unlocked the character cards (in the Heart menu) for Asteria, Luna, Roxy and Qarinah. Second, you need to have unlocked the Nexus (via Morgana). Once you've done both of these things you need to sleep and then the next time you enter the Nexus something weird will happen...
Hope that helps!