Auriga, yes, good to Be Firm about dogs. And timings.
I would vote for your dd to be Head Girl. Where can I send my ballot paper? 
Sadly, my dd has now taken to her bed and refused to go to school at all. I went in at 7.30, she ambled downstairs about 9ish, had some breakfast and went back to bed. I emailed her tutors. Then later I went into school and managed to have a chat with one of them. I have given the tutor the full story, including the details of the extreme behaviour that we had to deal with over the summer. Essentially, I think everyone's view is that there is nothing to be done. The school is going to take a hard line about laying down the law the next time that dd makes it in there (assuming she ever does), but they are highly sceptical about it making any difference. As am I, tbh.
When I got back, dd was still in bed. And is still there now. She said that she had nothing wrong with her and was just "tired" and "having a lie-in". Her attendance so far this term is slightly over 50%. She also told me that she did not have anxiety or "any headache stuff". Yes, the diagnosis of cluster headaches is allegedly firm, she has seen 2 GPs and an A&E doctor. However, I suspect that our GP is wondering about some things in relation to this diagnosis and dd's, er, creative abilities.
After further investigation, I think her line about the driving not being ok with the medication was a reaction to the driving instructor asking her if she was ok to drive. She has now had 2 really bad driving lessons where anxiety has prevented her from doing anything, pretty much, and I think the driving instructor is wondering what is going on. Of course, dd is blaming her inability to drive on the fact that I will not agree to getting our car insured for her to practise in at the moment.
So there we are. Guess I will indeed just have to step back, but the problem is that if she reverts to the violent and threatening behaviour we had in the summer, stepping back will not be enough. It's all really very sad.