Anyone know what the rules are for checked bags on a SDFC? Wife was on FLL-CLT-PHL route yesterday and got in early to CLT and wanted to SDFC to an earlier CLT-PHL flight. She had no options in app or website. I called in and they said she couldn't due to status and that I, as an EXP, would be able to but since she had no status she couldn't (huh? no mention of fees - just that she flat out couldn't as availability was different based on status - flight was wide open - 7s across the board).
I later figured out (due to a helpful AC agent) that her lack of options was likely due to her having a checked bag, which the phone agent probably didn't realize or wasn't able to see.
So, I am trying to learn what the rules are for SDFC with a checked bag on a connection in a situation like this as I always check a bag and may find myself in a similar situation in the future.
TL;DR: If you are on the layover of a connecting flight and want to move to an earlier flight (same destination) but already have a bag checked for the later flight, what are the rules?
Thanks!