Sway back sewers are a shapely lot. Getting the curves of a garment to meet our needs is a basic adjustment that I do all the time.
I'm working with Vogue 8931 and the pattern has a fold on the centre back. Easy peasy.
If you need to do a sway back adjustment, you'll need some shaping hence, convert the centre back fold to a centre back seam.
On the lining piece above, I've marked where the centre back seam should be. But I've also allowed for a centre back fold for a bit of jacket wiggle room.
The result is the lining pieces match where they should but you have a fold so the lining moves with you. I've had it rip before and I'm still haunted by that sound (shudder).
This new centre back seam gives you more shaping for your sway back. I also lower the centre back hem by 1.5cm. Now that's shaping where I need it.
By the way, I apply this same technique on knit fabrics too.
Don't just look at what I've done, go to some real references.
Singer Tailoring - 1988,
Jackets for real people by Alto, Neall and Palmer - 2006,
New Simplicity Sewing Book - 1979
Easy, Easier, Easiest Tailoring by Palmer and Pletsch - 1977