While possible, it's unlikely Marley has a food handler's certificate, required by every local health department (and probably the school board). She wouldn't be freely working in the kitchen with Millie, especially without some kind of hair restraint.
Sue would get fired for revealing Becky's grade to Brittany.
Rachel's lips are together when Brody snaps the selfie (phone camera makes a "click" sound), but her smile shows teeth in the resulting photo.