Taylor, Angie - that's the trouble with this alteration; you can't just do a straight-across seam because it would show, because of the way this vest is done... I forget the terminology but it's essentially "revisible" unlike a blouse where if you turn it inside out you see the seams. Does that make sense? I'm having a hard time explaining this. But, it's the reason vests can be really tricky to alter.
To alter a vest like this, you need to use a seam ripper to remove the seam all around both inside and outside layer, and also many inches down the sides of the armholes - front and back. Enough inches to be able to completely turn the garment inside out. Then you re-sew the shoulder seams where you want them (with a slope). Then you have to turn it back out, and hand-sew the sides back up. So it's not really a simple matter but rather involved.
Maya, this is a lot to digest, but... maybe it offers a permanent fix for sloping shoulders?
http://www.elitefitness.com/fo.....53355.html
If you don't want to get into weight lifting, reading through this, my take-away is that flexibility is highly important. Yoga may help immensely. You may be tight in certain muscles that are pulling your posture awry. The sloping shoulders could be a symptom of future back and neck problems.
This is just a guess... sloping shoulders are not an issue I've ever had, though my mom has sloping shoulders - but I obviously did not inherit them, if this is inheritable. So I may be completely off-base here!!!
However, I would say it is worth a try to improve flexibility - *especially* if you are having any back or neck pain!
