Well it wasn't JUST for Daphne to scream. She was going to scream that a rat had escaped, jump on her desk, and then pretend to faint. So we'd have people running around and looking for the rat, and we'd have people fussing over Daphne, and the idea was to disrupt things completely and give me time to get out (and yes, I was supposed to get behind Vince or Greg, though I don't think they were looking at Draco so I'm not sure they would have remembered this was part of the plan.)