Alterations: How to lower front waistband (& keep back high), w/o changing hem grain line?

I am trying to sew pants/skirts for my daughter, who prefers a "low-rider" style in front, so it pushes beneath her buddha belly (short-rise in front), but still needs to be higher in back. I understand flat-pattern alterations, but cannot figure this out immediately. I can't simply cut off part of the hem in front, as it would change the grain line, and I want it to be even horizontally, of course. So, on pants/skirts that have a simple fold-over waistband (lazy days skirt), how do I lower that front, and still allow for a smooth fold-over (while needing it 2" lower in front), without taking it off the hem? And in the case of pants, such as the Sailboat pants, that have a tailored front, same question? I hope this makes sense… to make it easier, I'm attaching an image of what I'm trying to do (lower front waist): third image.