|I have been machine-quilting a heavily padded fabric sandwich, and had problems with the bottom layer - the layer closest to the feed dogs. Little tucks would form when stitching, and there was no way to control it. Since I quilted the sandwich with the top layer down (with nice thread in the bobbin), I could not ignore the tucks. Rip, rip, and then hand quilt past the problem spot! No amount of thread basting would help.
Theoretically, the layer closest to the feed dogs should get easing help from the feed dogs, but in this case that wasn't enough. When hand quilting, I draped the sandwich over my hand (with the top side up), and this helped easing. This gave me an idea: if I could machine stitch with the sandwich draped similarly, the tucks might be avoided.
To accomplish this, I lift the front of the sandwich as high as I can to get a rounded shape as the fabric enters the feed dogs. It works even better than I imagined: no more tucks at all, and the quilting looks really smooth on the top side.
I imagine that this method could be used for easing bottom layers in many situations, not just for quilting.