Before I finally mastered mitered corners, I would round off the corners of my quilts, (I used a dinner plate for my shaping) and the bindings went on great and they look nice the way they hang from the bed. Maybe you could try "killing with kindness" when the old folks are being hyper critical. Tell them you really appreciate their advice and maybe someday you will be able to do it "as well as they do". I bet that will make them hush.