What is your exact fare code?
That being said, many of the fare codes between BOS
on US Airways allow for up to 3 connections each way, with PHL
, WAS (in the case of US, you're talking DCA
) and NYC (in the case of US, you're talking LGA
) as the legal connection cities.
That being said, ExpertFlyer is showing the BOS
flight at Y9B6 etc. and the PIT
flight is very open (9s in every fare bucket out there).
You can try doing it at PHF
but you might have to wait until BOS
to do it (for some idiotic reason, US Airways makes you do the same-day travel changes when you're physically at the airport, rather than through calling reservations, which is what every other airline lets you do).