All of the comments about Guanfacine almost have me sold, but if it isn’t enough to manage the behaviour in the evenings then it won’t work for us. My daughter isn’t “hyper” (or at least not enough that it’s a problem), for her it is the impulsiveness which leads to the defiance and mouthing off. It is extreme in the evening and that is when her PTSD kicks in (she’s scared to go to bed) so I must have the ADHD completely under control so we can tackle the other stuff.
I will definitely ask her paediatrician about it, though, because it sounds like it could be an option!
Thank you all for your replies!