I have to make some additions on this. It was brought to my attention that I was doing this on a log cabin block, which has straight edges. Not a problem with the sashings coming over the top. BIG PROBLEM WITH POINTS!!! So.....I will have to add some guidelines as not to lose the points.
Say the top block is 12.5. Batting should not be cut to 12.5, but to 13.5 inches square, backing piece should be cut 15.5. AFTER QUILTING THE BLOCK, cut the batting to 13 inches square, there should be 3/4