Will miss a fly segment
 

I am new to this forum. Bought 2 UA tickets(w class) for me and my son (12 y)to go to Paris, France to see my brother from PHX in 2 weeks. We were suppose to fly back together. Now, my brother is going to take my son from Paris to China to see my dad. That means my son will miss the segment coming back from Paris to PHX. Should I inform UA about this change? Will I get any credit for the segment my son is not going to fly?

If your ticket is refundable you may be able to get a partial refund. If it's non-refundable there may be a credit to be had.

You should call UA and have them look into it. You may have to pay a change fee and the fare will be recalculated based on the current One Way fare. Any remaining funds will be issued as a voucher you can use on a future flight (within 1 year of your original ticketing date) or, if refundable, a refund.

One way tickets to Europe tend to be expensive (think B fare), and thus the refare associated with making it a one-way is likely to leave little or no money for a credit. The best you could probably do is find another date (within a year of original purchase) to reschedule the CDG-PHX leg (you may be able to change cities). If you don't have a reason to do that, it is likely that your best course of action is to simply not fly the return. It won't be a problem if your son doesn't make a habit of it.

maybe you can use ticket for him on return trip [from China? from france?]

The change/cancellation fee isn't payable until the credit is used. It's likely $250-300. So long as the residual voucher exceeds the change fee, it's worth having the voucher. If you never use it, you lose the value, but you haven't paid out more cash. If you do use it, you will pay the fee.

Thank you so much for all the response. These are very helpful.