The method I used was to sew down the applique with a satin or blanket stitch, then position the block/quilt over a piece of batting slightly bigger than the applique, on the back side, and pin in place. From the front, topstitch around the applique in the ditch. Carefully cut away the batting from the backside, leaving only the shape of the applique. When you layer the entire quilt
that section will have double batting and stand out from the rest of the quilt. I used this method for the silhouette of the soldier in this quilt.
Veterans quilt to honor three generations