In fairness, Perp a lot of it too would be to do with your df's behaviour I would think.
Taking Fair's example further;
if, when I met now dh and we were all going out, he said to me "look, Jane is struggling with this, she's unsure about how things are going to be and sitting in the front is her 'thing'. Now, I can explain that it's more respectful for adults to sit in the front but would you mind if we both said she can sit in the front on the way there as a little treat, but that adults sit there, and we'll ease her into the change" I would think, ok easing her in fine.
If he had said "the front is her's, get your arse in the back" that is most definitely not ok.
But that would be him doing it and nothing to do with Jane. Even if she felt smug about it, she's not the one who put us all in that situation.
Unfortunately, a lot of stepmothers would take it out on Jane; she's being a cow, she's a spoiled brat, she needs to learn her place.
Well, no. Her father needs to learn to teach her 'her place'. Why on earth would she voluntarily change the status quo in a situation that's completely new to her anyway?
And therein, I think, lies the problem.