I've done this on several quilts. I sew the strip down after carefully laying the new strip on top of the already sewn-down strip. I actually bring my iron over to the machine and iron the piece so that the seam is not at all bunched, etc. After the seam is sewn and ironed, I may do a quilting pattern across the strip. Then, I just keep repeating the process. I was unsuccessful in my attempt to add a photo; sorry.