I used one of my US Air credit card $99 companion passes to book a trip in early September for my wife and I .

Got the change of itinerary email and have yet to respond. We are now considering bringing our daughter on the trip. In hindsight I would have booked her at the same time and her ticket would have been one of the $99 companion fares.

So.... Can I just add her by paying another $99 or would I have to use the change of itinerary excuse to cancel the 2 existing seats and then just rebook for 3 people? I have a couple of extra of these $99 passes so I don't even need the other back. The fares for the flight haven't changed. Been successfully using these passess for years but never have been in this situation. Thanks.