At what point are DCs held accountable for their own actions, and their parents held accountable for their DCs behaviour?
It's nothing to do with being 'accountable' and frankly, just the use of this word says it all. It's not about scoring points, or holding someone responsible for a bad situation. It's about looking at changes that can be made to make the situation better. When this involves an adult and a child, then yes, I do believe the onus is on the adult to make the first move.
but he can (if he chooses) insist that she behaves respectfully. He is not doing her any favours by allowing this. Everybody needs to be respectful towards others, and this includes his dd.
But how do you know that it is not OP being direspectful too? That's the problem, many disrespectful people have no idea that they are, but they are so focus on expecting others to change their ways that they don't have an insight clue that they are not better than those they accuse.
My SM could have come here years ago if such a forum had existed and gone on and on about how disrepectul I was as a teenager. She wouldn't have been wrong because yes, I reached the stage when I was. What she wouldn't have bothered to mention though are things such as that despite be being petrified of the dark when I was 10ish and asked for my bedroom door to stay open and the hall way light on, she made a point of going to the toilet and turning the light off and closing my door despite my dad saying that it was ok. She also wouldn't have mentioned the day she came in my room and told me when she was clearly angry 'Well Miss X (my mother's surname rather than my dad's and hers'), you don't belong to this family'. Those are the main things that have stuck to my mind because they upset me greatly, but there were many other actions that had a significant impact on my feelings that led me to wanting nothing to do with her.
Time has gone by and we have amazingly rekindled our relationship and get along brilliantly. Last year, she told my husband that she had massive regrets with the way she handled the situation, that she was young and way to focus on my behaviour, which was actually nothing but typical kid/teenager, but she couldn't see this at the time. However, she has forgotten the above events, probably because they were not significant to her and quickly forgotten, whereas they stuck to me for many years.
So indeed, when there is conflict between a SM and a child, and the child is accused of being disrespectful, I don't always assumed that it is only in one direction.