Join shoulder seams and side back seams by tacking. Now it's time for a fitting and small changes can be done on the side back seam and/or the shoulder seams. Stitch seams of shell only and press open.
Fold lining of back towards front and tack to seam allowance of side back. Tack and stitch with zipper foot close to the seam line.
Fold lining of front towards back and fold under. Pin and tack in place and hand sew to previous stitching line.