BoM/TWS Message Forum

"some girl named Jenna, some girl named Johanna"

My guess is that "Jenna" refers to Jenna Greeley who's an Eastman student while "Johanna," based on the likelihood of "Casey" being Casey Sennik, is Johanna Olsen who's on Schuyler's volleyball team. There's a lot of characters that exist as names and faces in a supplemental character list who have never so much as appeared in BoM proper or even in the wiki and those are, I think, two of them.

The presence of middle schoolers and the fact that Robert seems like patient zero also makes me think that it's not high schoolers but a group of middle schoolers behind this.