The shoulders are worked with separate strands of yarn. K23 sts, drop that yarn, put 23 sts on a holder and with a new end finish the row. Then turn and work the next row with the same yarn, drop it and pick up the other yarn after the gap, BO 3 sts and finish working that row. Turn and begin the next row, drop the yarn, pick up the other yarn and BO 3 sts and finish the row. If you do it exactly that way, you'll see how it works out when you get there.