Originally Posted by Zorak

Google finds some hits from late last year stating they would be leaving SkyTeam but UX's web site still mentions SkyTeam and lists DL as a partner https://www.aireuropa.com/en/suma/su...partners/delta

of course they could just be slow to change.

If it's still technically possible, then yes they should be able to do it at the airport counter or gate.

I think call times are pretty bad right now but have you tried calling and asking if they can enter it manually? You can also try Twitter or Facebook private message, or the messaging functionality in the app (the response time might be equally long but at least you won't have to sit around on hold). If DL won't do it in advance or at the airport but you're pretty sure UX will still let you credit it to SUMA (or if you don't have any place better to credit this) you could as a last resort try flying it w/o FF info and submitting it for credit after? But ultimately this seems like more a UX question than a DL question.