The domette arrived! I cut a generous piece for each side (about 2-3 inches larger than the chest reinforcement) to work in some of it as fullness while still being able to cover the prickly edges of the hair canvas. Domette is a thin piece of lofty cotton fiber (think a cross between flannel and quilt batting only much thinner). I attached the domette with long basting stitches, the fullness will be distributed while pad stitching this piece to the hair canvas and the larger canvas beneath it.
After placing the lapel twill stay tape and spending hours pad stitching the layers and shaping the lapels, working in the fullness… I didn’t manage to take any photos of it before assembling the coat. I could use the excuse my stitching isn’t very consistent, but I flat-out forgot to take the photos. Not even on the collar!