To the OP - you can have the reservation agent break out the itinerary into two segments manually. They are very reluctant to do this. I recently was booked on NW 209 BOS-DTW-SEA (DTW-SEA wound up cancelling though). I could not, for the life of me, get any agent on the phone or at the airport to break out the flight into two segments. Many people on the board have reported success.

If it's broken out into two segments (regardless of whether it's the same flight number), it will post as two segments in your account and you would earn 1000 miles (500+500) instead of 528 (BWI-GRR mileage).

Also, FYI, if you booked it on the website as a multi-city itinerary, you could also earn two segments and 500+500 miles. I know it was a schedule change that has caused this problem though.

My recommendation...call NWA and beg & plead for them to break it out. Keep calling back if they keep saying no. You will hopefully eventually get someone who will help you.

-RM