Perhaps, but again it down to the question of if you have two separate ticket stock numbers for these flights. Do you have two separate e-ticket numbers for these two flights? If so, you should be golden. If they are indeed separate reservations, my suggestion is to call NW and have them associate a different SkyTeam-compatible FF number (e.g., a CO account) with the flight portion you do not want credited to your WP account. If all of your flight segments have the same e-ticket number, however, then this won't work.