Originally Posted by
Tartan
When you draw the line, that is the folding line. Sew beside the line on the outer edge. This should give you enough extra fabric for the fold over. Check before trimming the extra triangle fabric away. You can also OVER cut your square that goes to snowball the edges and trim after. I love Lori's patterns!
I believe Tartan has stated it very well. Stitch your folding line just a thread or two toward the outside of the corner.