I have been quilting for many years and have never added corner stones to a quilt border without specific written directions. I am doing a crazy quilt for a special friend and it does not have a pattern and I am adding a sashing to it and am less than an inch short on the corners. How do I add corner stones to make up the difference. My pea brain is on overload tonight & not working tonight . Please help, I feel so stupid as I should know how to do this.