I have an Advance booking for two with a Two Together Railcard. I need to rebook, preferably for only one person in the party. When rebooking, I need to select a reason. One of the possible reasons to give is “Split party travel arrangements”. There is a free text field “Additional information”. If I leave it blank, I get an error message with “Additional information is required when using the selected change reason.”:
Under what conditions can I split a party when amending an Advance railway ticket with a Two Together Railcard, and what information would I need to provide in the free text field for Additional information?
Prior to me asking this question, there is exactly one Google result for “split party travel arrangements”, and it does not contain helpful information.
In case it matters, I booked my tickets from First TransPennine Express.