My MCI DL 25K finished posting 10 days ago. My mother switched to sprint on their 25K NW promo. I called MCI and told them I would switch unless they could match it.

They did but told me I would have to pick another airline because I had just received mileage in the DL program.

This info would be in your mci account history. I seriously doubt they cross reference or index based on FF account number and be able to tell that a different mci account had earned partner miles.

Go for it!

TW