I have been thinking about getting one of the Eton Jackets from Uniformwearhouse as a compliment to the tails coat I converted to a PC. My questions is if you replaced the original button and added the six side button and cuff buttons with button held in place with cotter pins, could you also carry a set of buttons covered in black cloth matching the coat, could the black button be used to make the coat less formal - almost day wear.

Rather than carry two coats you could carry two sets of button.