I've bought cheapie tickets to fly with my family from A to B, but due to a work trip I want to skip the return flight back to A and instead do the business trip from B to C and return C to A. I've got 2 concerns about not showing up for my return trip from B back to A.

1. My family is on the same reservation and if I am not there they won't let them fly.

2. I will be "back charged" (not sure the right term) for the difference between the cheapie round trip fare and a one-way fare. I've read that this is done to travel agents, but am not sure if it is also done to consumers.

I'll be flying from A to B on United so I have confidence that they won't do the right thing and look the other way. I booked the ticket from united.com so I am concerned that they will just add a new charge on my credit card.