Finally, I can start building this corset. After picking out all the seams from the try-on, and ironing the fabric, I was ready to start sewing.
I cut the pieces for the cording on the fold, and placed the first one on the center front piece, matching the notches at the apex. It fit exactly as it should. Whew. I pinned the bottom layer to the adia cloth, and tucked a piece of crochet string inside the fold. I sewed the pieces together along the cording.
The new top edge has been marked by basting a line with red thread instead of cutting the excess fabric off. I can trim everything when the corset is sewn together. This is probably where tailor's tacks would be useful, I'll have to learn how to do them.
Anyway, because the bottom layer was pinned in place it couldn't bulge under the cording. It stayed flat and the top layer accommodated the string. Each time I laid down a piece of string I grooved along it with my finger nail to help the top layer fit snugly over the string. I sewed 7 rows of cording this way. Then I measured 1/4 inch, laid a piece of string next to that space, trimmed the seam allowance off the bottom piece, and tucked the seam allowance from the top piece under.
I stitched the cording in place.