It's YA if the kids are elevated above the adults (i.e., the adults are incompetent and/or clueless while the kids are smart and knowledgeable), and the plotline is kept relatively simple, and if the story is focused on the kids as main characters.
For example, The Crucible is about kids pulling off a hoax and the adults are incompetent and gullible (for various reasons) but the focus is on the trial, the consequences, and the outcomes. If you did a re-imagining of the story which followed the girls through planning sessions and talking about how they were going to get away with it and about how it was getting out of control and one girl broke free from the pack to try and stop things, then it'd be YA.