Sandwich the back bodice between the two yokes, sew and press. Top-stitch the seam if required.
Roll the whole back body up with the right side on the inside then pin to keep it out of the way.
Pin front shoulder to top yoke shoulder seam and sew. Roll fronts up and pin to keep out of the way.
Cover the rolled pieces with the under yoke, then to sew the front yoke seams together.
Pull through and turn out to the right side. Top-stitch the seam if required. Stay-stitch the two yokes along the neck.