Even more gutted .... the second marital fight

Thanks for the helpful comments and a special thanks to Ruth for sending me more fabric. I will have another go next weekend after a decent interval. Having said that, I do hate to have unsolved mysteries, so I am considering a really quick, calico muslin, complete with vertical and horizontal balance lines, to see if I can work out if it is the grainline or not since not knowing what is wrong will bug me.
Becki, I do have Pants for Real People and as far as I could tell from the diagrams, they suggested raising the pants at the back which would be my next stab at fixing these if it turns out not to be the grainline. I also have Leichty, Potberg and Rasband's Fitting and Pattern Alteration book which, because it only has diagrams and not photos, for some reason works better for me when diagnosing problems.
Peppermint Penguin, the trousers are at the natural waist, but I have a very long lower torso which gives the impression that they are high waisted. It does look a bit old fashioned, but I am really uncomfortable in lower waisted trousers and spend all day trying to hitch them up.

OK, these I don't need to ask you about. These are a disaster of epic proportions. But its only fair to post the bad with the good and I have a fair idea why they look the way they do, which is certainly the only good thing to come from this whole week of wasted work.

I am particularly gutted about this pair because they took me ages to do, the fly was utterly perfect, and this embellishment on the pockets took me three evenings to achieve because beading just isn't my strong point.

OK and now for my initial impression of what went wrong. See the photo below. I don't think that I was careful enough with my grain line markings. Oh, I was sure I had it right at the time, and I did line everything up carefully... but obviously not carefully enough. The heavy line is the new grain line which I have added. The lighter pencil line is the grain line I was originally working off. They are off by over five eighths of an inch. Now I am not entirely sure this was the cause of the problem, but am working on the basis that I should alter only one thing at a time to try and diagnose the problem, and the problem does appear confined to the back pieces in both cases. I've also altered the yoke piece slightly to take out some excess at the centre back. I am slightly hollow there, and Marfy drafts for a more curvy derriere than I possess, hence the excess fabric.

Of course I don't have enough fabric left to cut two new backs.

Because the grain line is off by so much, I can't recut the existing backs because I won't have even a scant seam allowance at the back crotch curve and in any case I clipped that sucker really well. It would be a recipe for a wardrobe malfunction.

I don't think I can cut new backs with a seam across the leg as it would look bad.

And I can't think of any other solution.

I reckon tonight will be spent de-beading, de-zipping and de-lining these ready for attempt three. I should be able to reuse all those items in future pairs because eventually I will bend this pattern to my will.

I don't have any fabric suited to making attempt three, having used up almost my whole suiting stash on my week of failed trousers. I only have really nice stuff left, and not enough of that to sacrifice any on the altar of "it might work". I think my local cheap fabric shop had some pin stripe poly mystery stuff in the sale that would be suitable for a "might work, might not work" garment but I can't get to the store until next weekend.

I do wonder about the wisdom of starting on a pair of jeans tomorrow, though the jinx has to break at some point, doesn't it?