Mid-route changes?
Assume a route such as OAK-LAX-MSP-BNA, with OAK-LAX in the evening and LAX-MSP-BNA after midnight.
Once one has arrived LAX, what change options are available-- can one SDC or standby at this point, and to what flights?
Similarly assume OAK-LAX-ATL-BNA, with arrival to ATL early morning.
Once one has arrived ATL, can one SDC or SDS to an ATL-BNA flight later in the day?