Firstly can I just say I love the idea of all the Neverborn children ganging up together.
I don't have my book 1 handy so can't be too productive on tips. As far as I recall though, Kade has some synergy with Teddy, who is a Nightmare, so that is something to look at.
I can't remember if Teddy gets called to Kade or the other way around. I hope it's Kade to Teddy as that would be more advantageous for you, but I don't think it is.
As for Candy, no direct synergy but a nice support model all the same.
This is showing me just how long it has been since I used either of them, will have to rectify that.