how much are you looking to increase the waist by? If it’s not a great deal, I would simply add to the skirt pattern pieces that end up on the edge of the finished skirt. With a wrap skirt like this, I think it’s a little easier to keep it simple. Let’s say you want to increase the waist by 2″. Take the pattern piece that goes on the end, on the end edge side, just draw a new line all the way down that’s 1″ out from the original line (if it’s going to be cut out twice, to give you a total of 2″). so instead of doing any pivoting at all, you’re just redrawing the side of the pattern to give you a little more room. This skirt basic in it’s shape, like most wrap skirts, and, therefore, more forgivable.