The other 11 girls Took a Level in Dumbass
while Madeline stayed at the hospital in the first TV special ("First we brush our bread, and then we...break our teeth?") because they are physical manifestations of Madeline's imagination, and didn't know how to function without her. Madeline also created Genevive to save her from drowning, and granted Genevive the relatively high intelligence she demonstrated during class. Pepito also sprang forth from Madeline's imagination because she wanted a cute Spanish boy to live next door.