I think it likely that the boots are adjusted TOO LOOSELY, so that she collapses forward in them and then must compensate by sitting back so that she doesn't lose her balance completely. We see this with many, many students. To repeat, hips back are often a symptom of boots being too loose, rather than too stiff.
She's planted firmly on the back of the boots, because they offer support while not restricting the ROM for balance. It's typical.
She's gliding a lot. Not really turning much. The priority would be to get her to actually turn across the slope some.
Braquage, pivot slips and developing a good hockey stop is important.
At this stage, a lot of it is a range of motion awareness issue. They have no clue how much range of motion they need, to put the skis on edge, to balance on that edge etc.
Get her to touch the boots in transition. Touch the toes throughout the turn. Touch the outside boot. Airplane turns while touching the outside boot. Touch the snow. etc.
Develop the balance: take a ski away. Hop turns, shuffle turns, step turns.
Once she starts to show some awareness of the body, then you can start with some technical development.