I'm not really sure. You might try calling CO and NW and see if there's a different PNR code for your "NW" itin vs. your "CO" itin. I booked an NW ticket on KL metal a few months ago, and couldn't view my seats on nwa.com. A call to NW netted me a different PNR code for KL, which I was able to use to view my seats on klm.com.