A solid amount of flights out of SFO end up delayed for various SFO things; ATC congestion, bad weather, etc. On DL, almost every delay triggers the “select alternate flight” feature of the app.

I’ve used this feature several times to get more MQMs/MQSs but I’m curious where the rules for what you can re-route to come from.

For example, I once changed SFO-BOS to SFO-LAX-JFK-BOS. (DL then paid me 10k miles to switch back to SFO-BOS because of overbooking.) How does the app decide what routes I’m allowed to select?

Also, is it ever possible to add a stopover? In my current changed routing, I changed SFO-SEA-CVG to SFO-SEA-ATL-CVG. But would it ever be possible to add a stopover in SEA?

if you have any human interaction during the initial rebooking you might be able to get a longer-than-4-hours layover — which would technically be a stopover rather than a connection — but I sure wouldn’t hold out hope for much more than one or two flights later

that said, if you were rebooked onto the SEA-ATL redeye, you might have a case for a morning flight as long as you were explicitly willing to pay for overnight accommodations

I make that last point from experience: a couple years ago I booked a sunrise BWI-ATL-SEA at ~T-15 hrs when there was a weather waiver in place for the next day ... went directly to DCA, asked for either of the two remaining ATL flights and the earlier ATL-SEA (763 with lie-flats) in the morning; counter agent quickly confirmed me on the later flight once I said I already had a hotel reservation