The way I tried before had you do front and back connecting strip more or less at the same time. You stitched both front and back connecting strips to the original square in a single seam onto the original square. Then you attached the next square to the back strip and topstitched the front strip to the second square.
I only did it as a 3 square vertical wall hanging so I don't know how the rows were to be put together. I'm guessing it would be done the same way as adding squares. Maybe need cornerstones?