Originally Posted by
boxo
Thank you. The chat agent was able to make the changes with no fare add/collect. She said I wasn't able to do it myself because of the KL segments, two different airlines, which doesn't make sense with KL and DL being partners for so long... but I am not accustomed to flying SkyTeam or making changes, so what do I know.
ETA: I also mentioned to her I was not able to save my credit card info in the app - the submit button did absolutely nothing. In the midst of my multiple attempts at trying to make the changes, I thought I'd add the payment method for convenience to no avail.
ETA again: Just for kicks, I thought I'd see if I could manage future changes, but NOPE, it errors out again with a different message.

This is pretty normal for Delta. The online tools work great for domestic, but for international I always have to chat or call in (chatting I generally prefer, as it can take an hour+ call).