I just finished quilting a vintage quilt with waves of fabric in the top and bottom borders that I had actually added after having carefully measured. After ripping out and re-measuing and reattaching, I ended up pleating four areas equally spaced apart, which quilted out fine; but then as I progressed through the quilting there were pockets of gathered fabric that were not obvious when laying out. When completed, all had quilted out just fine. Keep in mind: "vintage".....and the owner also had it stored for at least 50 years. Just as a resource, check out Love Bug Studios Blog if you can find it online and her recent post on December 3 highlights the very crisis you are describing. Good Luck!