This isn't sdc -- but as a diamond MM I just called and asked for a reroute on an inconvenient routing. The OP is DL silver so may not get quite the same response, but worth asking.
I had originally booked DCA-ICN RT with a double connection to get to my international flight that meant leaving DCA at 6 am (was about $300 cheaper with the multiple connections). About 3 days before departure I called and asked if there was any chance of a later flight direct from DCA to the international departure.
The kind agent checked and came back with a non-stop to the intl departure city. No charge -- I did lose the GUC domestic upgrade but got it back at the airport on departure.
(Note - I thought about sending in a compliment for her work efforts, I had her name. But wasn't sure if she had maybe bent some rules for me and didn't want to get her in trouble. Interesting because she thought she would have to call the international desk to get them to revise the ticket, but was able to do it herself. And finally, the MQDs for the trip posted correctly.)