Here's what I want to happen in the next book(s):
-The twins turning 13 and their birthday party.
-Heimertz and Madame Dahlia having kids of their own.
-A very humilliating defeat for Stephanie.
-The twins' parents, or at least for them to be mentioned.
-More parent/child moments with Nod, Heimertz, Madame Dahlia and the twins (I would love to see some interaction between Dahlia and Edgar, as well as Nod/Heimertz and Ellen).
-The twins joining the Midway Irregulars, at least as honorary members.
-Imogen and Edgar getting together.
-The twins wearing something that aren't footie pajamas. -Nod and Benedict meeting face-to-face.
-An epilogue with the twins as adults and with kids of their own.