When I have fullness, I place 1 can of vegetables on either side of my longarm needle. (Green beans are what I usually use, but that doesn't really matter.) The needle will not hit the cans as they roll as you quilt. I have been able to ease in a great deal of fullness this way, but not always all of it. If I have to take a tuck, I try to line it up with a seam in the body of the quilt and it seems less noticeable. I know what you mean about not wanting to tell an older lady that she is doing something incorrectly. I quilt for a 88 year old and she does beautiful embroidery, but her borders are almost always wavy.