Five or nine pieces

I draped out the underbodice for yardage purposes as your general corset style job, with princess seams and ending up with seven pieces. The book says the outside of the underbodice is five pieces. Two fronts with double vertical darts, two side backs and a center back. The lining is nine pieces but it doesn't say what they are so I will keep thinking on that.

I drafted one of these dress fronts with the vertical darts. After making it up in muslin, I'll figure if I can then cut it down to make corset-like fronts. It should work but I'll probably have to do something about that side dart.