I had to look it up since I wasn't 100% sure how it would work for partners, but here's what's on DL's website page for FAQs on MQDs regarding earning MQDs on partner flights: "Flight spend for travel on other airlines ticketed through a Delta channel (featuring a ticket number beginning with “006”) will also be included in MQDs." So yes MQDs spent on JV flights and Skyteam partners MAY count towards MQD of you book it the correct way. Given DL IT, I have my doubts on how well that will work though.