Sweater so far. Left front stitches are on waste yarn and right front is ready to be worked.
The crossed stitches at the center front will provide reinforcement at the bottom of the neck opening.
RIGHT UPPER FRONT:
Work back and forth for 10 rows, keeping pattern as established and ending at the shoulder edge. Break yarn, leaving about 4 feet.
Use your preferred method to attach the shoulder stitches to each other. Either use a Kitchener Stitch from the "right side" to graft 12 front and 12 back shoulder stitches together, or turn the sweater wrong side out and use a 3-needle bind off from the "wrong side". Keep the last stitch "live, and place it on a stitch holder along with the 8 neck-edge stitches.
(Hint: do not fasten off the yarn used to graft or bind off the shoulder seam. Leave 6-8 inches of yarn; you can use this tail later to draw up any slight "holes" at the shoulder after working the collar).
LEFT UPPER FRONT:
Take left front stitches off holder. Join yarn at center front. The wrong side of the sweater should be facing you. Beginning with pattern row 3 (and keeping neck edge section in garter stitch), work back and forth for 10 rows, ending at neck edge. Do not break yarn!
Place back left shoulder stitches on a double-point needle and use reserved yarn at shoulder to graft shoulder seam (from right side of sweater) or work a 3-needle bind off (from wrong side of sweater). Again, leave the last stitch "live" and place it on the circular needle next to left front neck stitches. Again, break shoulder seam yarn, leaving a tail for later.
Pick up the yarn at center front and with wrong side of sweater facing you, knit across 8 front neck stitches, 1 shoulder seam stitch, 16 back neck stitches, 1 shoulder seam stitch and 8 right front stitches.
34 stitches total.