I decided to "Frankenstein" it with the Belgian Military Chef Jacket to get the pattern for the Imperial Officer uniform. Specifically, I'm using the back, sleeve, and peplum pieces from the Frock Coat, and the collar and front pieces from the Chef Jacket, with a bunch of adjustments. A soon as I figure out how to use the drawing program, I'll post some illustrations...ok so this is really terrible. I think I need one of those pads with a stylus or something:
The red lined pieces are from the Belgian chef jacket, and green line is the frock coat. Blue line is my modification. Using sleeve and back pieces from the frock coat as is.