Assuming there is availability, can I SDC to an alternate routing to get to my end destination earlier? I need to go STL-XXX-GRR tomorrow, and am currently booked STL-MSP-GRR, but Delta is show routings open for STL-DTW-GRR, STL-ATL-GRR and STL-MSP-GRR, all with more convenient schedules then my original ticket.