Birthing a large quilt can be done. I find it easiest if you have two people doing it. Pull out corners, lay flat and place an occasional pin throughout quilt. I then use the same method as for smaller quilts closing the opening with pins and go around the whole border and pin or use clips to get joining seam to lay flat. Then I use a decorative stitch around the whole quilt and use same stitch to do some "quilting" to hold the quilt together. Just a little more bulk to work with.