First award saver seats are hard to come by regardless of season to Europe. Summer is difficult for all saver seats to the Continent.

You're doing the right thing by calling everyday since inventory changes daily. If you find a couple seats that might work, make sure to reserve them. They might be gone the next time you call back. You can always cancel the hold on them if you choose not to book them.

I'm not a SkyTeam flyer, but I thought I read that different availability showed up for CO/DL/NW at times. Try searching the SkyTeam and the CO/DL/NW boards.

If you called NW and found availability, you'd still have to call DL for them to find it and use your DL miles. You don't have enough miles in any of your other accounts for two Europe tickets. Good luck.