Pin interfaced waistband to blouse, right sides together.
Grade seam allowances. The seam allowance with interfacing is closest to the outside of the garment so do not trim it. Trim 1/8" from the middle seam allowance and trim 1/4" from the innermost seam allowance which is the waistband facing.
|Note the alignment of the side seam; the side seam above aligns with the side seam below the waistband.|