Originally Posted by NJ Quilter

I put a pin straight down through the seam/point on the top block. Then put that same pin through the seam/point on the underneath block. Hold that pin perfectly straight up/down then place pins on either side through the 2 blocks and remove the up/down pin. This should hold your seam in place. I also (gasp!) sew over pins which I find helps things stay in place until they are sewn together.