i think you are jumping to conclusions regarding mr.Garvey.I mean the guy has the right idea but it's kinda weird that Mr.Garvey kind of just gets written out of the story. Also the Khalida plot kinda bugs me, I assume she's just going to end up raped by the fat kid but it's kind of annoying to me that she just gets randomly kidnapped by someone who isn't involved with her plotline at all. Like she isn't even part of the school cast, she has no connection to this character.
as for khalida, she was not involved with him before but now she is, because of the blackmail, so it's not really kidnapping.
I'm pretty sure she is part of the school and that's why she was invited for the party, we just haven't seen her before, it's possible more new characters will be interduced in the same way