Attach the waistband to the breeches body as shown with back stitches. There is slightly more waistband forward of the outer leg seam, and the back of the leg is gathered to fit. Note that the outside leg seam is finished as far as the button stand.
A quick pin up of the legs proves this pattern still fits. If there is any question, best to cut the legs with extra material on the inseam. Finish the outer leg seam of the lining and insert it BEFORE attaching the waistband. Stitch through the body and lining.
Flip the waistband up and press the fold flat. Pull the waistband lining down over the stitch line as shown and sew down. The next step will be the pie piece-shaped gusset at the back and a test fit.