Since I had purchased several small buttons for the sleeve vents, and because of the more unique nature of this jacket design, I decided to deepen the sleeve vents and have six vent buttons per sleeve.
I therefore needed to deepen the sleeve vent on the upper and under sleeve pattern pieces for the fashion fabric. Since the lining pieces do not have the vent in them, they did not need to be modified.
I increased the depth of each sleeve vent by 4 1/2 inches, which would allow plenty of room for the button spacing for the 6 half-inch buttons that I plan to use per sleeve. The total depth of the sleeve vent is 9 1/2 inches, excluding the hem.
Here are pictures of the buttons to be used as well as a picture of the sleeve pattern pieces modified for deeper vents.