I've got a trip this coming weekend that I'm flying BWI-DTW-DAY-DTW-BWI on NW metal, same day return. I'll have enough EQMs to get gold on NW this year by years end, so I'm not really concerned about the EQMs. Is there anyway I can do a FF switch? My DTW-DAY-DTW are on RJ's, so I won't get an upgrade & the extra 500 banked miles in NW don't really matter all that much to me, but I could use them in CO. I would like to fly BWI-DTW & DTW-BWI in F though.

Has anyone ever tried switch the FF number mid-itinerary & successfully been able to do it? If so, how did that work in terms of posting the miles?

Worse case scenario, I could just enter in my CO account number & fly Y the entire way (I'm confident I'll get the elite upgrade if I earn on NW as it's Saturday travel & the planes aren't super filled with elites).

Thanks!