Originally Posted by
goldelite8
I flew AAA-BBB (international) and have a return flight from CCC-DDD (international). If I need to cancel my return flight, what's the general rule with respect to retaining the value of the ticket? Unlike normal cancellations, am I restricted to using the ticket in connection with an international roundtrip ticket and would it need to include travel from CCC-DDD?
All partially-treated coupons are treated the same way. The general rule is that the return travel must be combinable with the itinerary that's already been flown.
Assuming AAA,BBB,CCC, and DDD are all different places, then your existing fare must allow for double open jaws (since AAA-BBB/CCC-DDD is a double open jaw). That's pretty much the most permissive rule you can get. Most UA fares will be able to be combined with this, provided that they cross the same ocean (if any) as your outbound, and that the open jaws -- the distances between BBB-CCC and AAA-DDD, aka the unflown legs -- are shorter than the flown legs.
So, it's not necessary to be CCC-DDD specifically, but it generally needs to be a flight in the same direction.
Alternatively, you can convert the ticket to a one-way and get the remainder as a credit, but one-ways are often much more than half the cost of the roundtrip, so it's rarely a great idea if there's an alternative.