I booked a trip last week through Delta.com for my wife and I to go visit family. It's a mixed Delta/Northwest itinerary (MCO->CVG->FWA Delta, FWA->DTW->MCO NWA). When I first booked it, I was able to select seats on both of the DL flights and put in for an upgrade on the one that wasn't a RJ. I wasn't able to select seats on the NWA flights. I assumed this was because NWA doesn't release seatmaps until 90 days out.

The schedule on my first DL flight from MCO to CVG changed. It now arrives 2 minutes earlier. On Delta.com, I can no longer select seats for it. The seat picking screen shows both NWA flights and the CVG->FWA flight, but there isn't even a tab for the MCO->CVG flight anymore. The NW flights still show no seat maps.

It's within 90 days of my NWA flights, but Delta.com doesn't allow me to pick seats. I was able to go to NWA.com and chose them there, and it even recognized my Silver Medallion status and let me pick some of the good seats. Even though I selected seats there, my Delta.com itinerary still shows no seat assignments for those flights.

I guess I have three questions for anyone who may know:
1) Why did the MCO->CVG DL flight disappear from my seat selector when the schedule changed? I expect that this is just a bug with the website.
2) If I chose the DL seats from Delta.com and the NWA seats from NWA.com, does it actually work? Is it normal that I can't pick seats for an NWA flight from Delta.com?
3) How do I put in an upgrade request for the NWA flights? It's a 757 from DTW to MCO, but Delta.com says it's an ineligible flight, and I couldn't figure out how to make NWA.com put me in for an upgrade.

I would have thought that the Delta and Northwest reservation systems would be better integrated by now.

Thanks for the help! I figure if I just call Delta, I could at least make sure I get the right seat assignments, but I wouldn't actually learn what's going on.