Not sure what you mean by Marketing Carrier.
all flights are operated by Delta (i assume this is what you mean by MC). I would be purchasing the ticket on AirFrance ticket stock assuming that gets me the 20%, which is a bit better than what I would get purchasing same itin on Delta stock
EDIT: Sorry, for some reason only saw the first sentence of TTT's original reply. Sounds like Delta knows how much I paid even if it's on AF stock and awards MQDs accordingly