Here are two different methods for stitching these right-angle seams: one you can use on normal fabrics and the other for more delicate and fraying fabrics.
Method 1: For “normal” fabric
overlapping the corner.
Method 2: For delicate fabrics
where the seam allowances meet).
to the stitches.
see, the organza seam allowances will allow you to stitch easily into the corner. Stitch, pivoting at the corner.