Suppose I've got an AOWE3 ticket, and the first legs are BOS-DFW-LAX. The ticket was written with a connection in DFW so that I can take a transcontinental non-stop later in the trip.

Now suppose I show up at Logan for the BOS-DFW flight, and a seat is available on a BOS-LAX non-stop. Would the check-in agent be able to put me on that BOS-LAX flight without reissuing the whole ticket?

(I know, it's heresy here to even think of a routing that yields fewer miles & points, but I've got a rebel heart.)