That’s a fair read of the post. Codes don’t stack: if auto-apply is on and someone arrives with a different code, the larger discount is the one that applies, and it’s still one code per product. PPP versus a code is the same rule — the buyer gets the better of the two, and the only way to force the code is to turn PPP off for everyone. On the Discover side, the documented fee line stays the flat 30% (processing included); there isn’t a published formula for the exact net after a code, so the sales CSV is the right check rather than invented math.

Thanks for confirming the one code per product rule. That alone answers most of the "can I combine these" questions sellers get before a flash sale, and the flat 30% Discover line plus the CSV check keeps the numbers honest.