Originally Posted by WineCountryUA

This is covered in the wiki -- but short answer O/D must stay the same but routing can change.

Originally Posted by emcampbe

Don't know the details of DLs policy, but believe their same day change policy changed within the last year or two to be closer to UAs.

You also reference standby, so not sure if you mean a confirmed change, or going for standby. If doing same day change, yes, you can change routing, as in your example of routing through ORD or IAD instead or EWR. Standby you can not change routing. Since there is no fee for either (as a gold+), its always better to do the confirmed same day change, assuming your same fare class is available.

If your same fare class is not available, none of the electronic options (kiosk, app, website) will allow you to make the SDC, but you can call an agent, who can make the SDC and still waive the SDC fee, but will charge an upfare from, in your case, the N fare to the lowest available fare.

Another option is to standby, however, that does not allow you to change route, which is pretty logical because there is always the chance you make it to your connection point but there is no space on onwards flights.