There's a sweater pattern over at Knitting Daily and a discussion about adjusting the sweater to fit. Hypothetically this is how I'd adjust the Corset Sweater if I was going to knit it for myself.
(I haven't tried any of these adjustments, so I don't how well they'd really work for real live knitting. I have no idea when, or if, I'll actually knit the sweater, so, like I said, it's all hypothetical. For me, ripping & reknitting are an assumed part of knitting to fit.)
Looking at the schematics, the 4th size hip and waist measurements look right. But I want a narrower neckline. I want a neckline width that's ½ - 1” narrower than the smallest size. The sleeves need to be the largest size. I want the finished seam-to-seam measurement across the shoulders to be 14” so 3.75"(times 2) for the shoulder straps, means a neckline of just under 7” (which is smaller than the smallest size). The 3.75" is the shoulder strap width for the 4th size.
Reading the pattern was trickier, too many different numbers (6 sizes, inches, and cm) for me to wade through. But as best I can tell it's knit in4 pieces, bottum up, and sewn together. The textured panel is just down the front center (and back center) for the neckline width, the rest in plain stockinette. The schematics (thankfully included) show some waist shaping and how wide the neckline actually is. When I knit the sweater, I'll copy it into a text document and removing all the references to sizes I'm not knitting, and probably reformatting the text to be easier for me to read.
So, keeping the sweater as knit from the bottom up and seam together, and keeping the same gauge of 19.5 st per 4," I would -
Cast on for the 4th size and,
Knit the front –
Do the bottom lace border
Set up the stockinette/lace pattern with 33 stitches in the center panel (according to a gauge of 19.5 st = 4”, 33 stitches is just under 7”)
Do the front up to the neck, doing the shaping for the 4th size
Bind off the center panel (which won’t be the same # of stitches as in the pattern since I have a narrower panel)
Do shoulder straps
Since I cast-off fewer stitches in the center for the neckline, I probably need more decreases either at the armhole, or at the neckline, or both, to get the shoulder straps the same width as the pattern. I can’t picture exactly where the extra decreases need to be. I'll figure out it when I get there.
I don't know if the smaller center panel is now TOO small to look good, maybe I'd start with the center panel the same size as the pattern and decrease gradually to the narrower width at the neckline. Again, I'll figure it out when I get there.
Back – follow the pattern, with the same stitch count, center panel width, and shaping changes as I did for the front.
Sleeves – the measurements for the largest size seem right, although I might add a few more stitches. Since I did the body in the 4th size, and I want the sleeves in the 6th size, that might make sewing in the sleeves a bit tricky. But basically, I'd just do the sleeves following the pattern for the 6th size and sew in the sleeves carefully. I might switch to making the sleeves from the shoulder down, just to be sure the length is right.
Cinch straps, probably no change from the pattern.
I’d switch the sweater to be knit top-down. Knit the 2 front neck ‘straps’, with a provisional cast-on starting at the shoulder, in plain stockinette, increasing for the neckline and armholes. Do the center lace panel, and do the side shaping. Do the lace border (or if doing it top-down makes the lace border look funky, pick another pattern). For the back, undo the provisional cast-on at the shoulder, work the back shoulder straps, increase for the neckline and armholes etc until the back’s done. Sleeves either wrist-up as written, or top-down. Sew it all together and do the cinch straps.