Translating step 9
Press the seam allowance on the new side seam flat and fold the top and bottom down.
Align the top edges of the inner and outer waistbands with the wrong sides facing together. Use straight pins to hold the fabric in place.
Stitch across the top of the waistband, right next to the edge. Make sure to begin where the original stitching ends to avoid leaving holes in the waistband.