Originally Posted by mvoight

I don't think you can use confirmed flight change to enable you to go from a city on one pnr to a city on another.

He is booked for OGG-DFW-MSY and MSY-ORD-PHL on 2 separate PNRs
He wants to now go from OGG-DFW-PHL and presumably return to MSY at some point. So, assuming MSY is his home airport, he is flying MSY-OGG OGG-MSY MSY-PHL, and PHL-MSY
He now wants to fly MSY-OGG-PHL-MSY (plus connections)

I guess the a possibility is to price that itinerary and apply his current tickets minus change fees to the new itinerary.

I think it might be cheaper for him to fly them as they are.