Originally Posted by
zhangbear
Extending a layover past the legal time limit (4 hours domestically) is only possible once you get to the layover point (i.e., after you land in C). At C, you can change to any other C->D flight within 24 hours, provided that there is availability. This can be done by kiosk/app/agent...however, agents may offer resistance if you try to change the date (i.e. original C-> D leaves at 2000 on 13 FEB, but the desired C-> D leaves at 0800 on 14 FEB)...
If you use the language "I only want to touch that one segment," you actually have a pretty good shot even before getting to the layover point. I've done it several times.
I've never encountered any resistance about moving to the next day, unless you mean from an airport agent. Airport agents are clueless about SDC.