I recently booked the following flights:
Ticket "A"
Thurs. SEA/IAD/BWI
Wed. BWI/DEN/SEA
Ticket "B"
Thurs. BWI/IAD/RIC
Sun. RIC/IAD/BWI
After the reservations were made, UAL changed the flight times on ticket "A" so that I would be departing from IAD to BWI on Thursday, prior to my arrival time.
When I explained my total itinerary, they were most accommodating about rerouting me as follows:
Thurs. SEA/IAD/RIC
Sun. RIC/IAD/BWI
Wed. BWI/DEN/SEA
And, they worked very hard to arrange a fare that was equal to the original fare and said there would be no problem whatsoever in checking my luggage straight through. I just need to show both tickets at check-in in SEA.
The bad news is that I lose 2 segments (1,000 status miles that I don't need, and 2,000 miles overall). The good news is that I save several hours and a lot of bouncing around that would only make sense to WebFlyers.