Hi, for what it's worth - I find that pinning through the points vertically holds the pieces in place temporarily, but then holding the pieces in place I use a very fine long quilters pin and pin about 1" away in line with the seam. If the pin is any closer it puts tension on the seam and it wobbles. I keep trying to think of something like a hair grip/money clip that would just slide over the edges which might be better. ps I don't take the vertical pins out until the seam area is relaxed if you see what i mean. hope this helps.