try this if you haven't already......when you mark that diagonal line on the small square, sew to the right edge of that line...which is probably just a thread away from the line.....seems to allow for the fold over. Also, when you do fold over and iron...if that now triangle is smaller that the square edge of that original rectangle do not cut that back triangle off.....use it as your sewing guide edge for attaching those flying geese to whatever element they go with.......sometimes the pressing of that fold over "now" triangle will be shorter and thus will make your geese "cockeyed" That seems to work for me..those little namol-measured differences add up in the overall finished product.