Has anyone had experience with this approach? (Haven't tried it myself.) If the phone agent says they found an itinerary that would work but someone else is in the record, effectively blocking it, could you just tell the agent to book the trip on a new ticket and pay for it, then wait for the record to unblock and sort it out then. That way, you have the routing you want and then you just need an agent to push through the change and cancel the "new" ticket. Granted, you could run into a "two overlapping itineraries" situation, resulting in a double cancellation, but I would think UA's system would recognize the IRROPS situation and leave it alone.