Notspaghetti I had a similar type of experience some years ago with my children, then 12 and 14.
They were going by train from Reading to Glasgow to visit their godparents on a slow cross country train, and as the train journey was long I booked them two window seats either side of a table so that they could play card games and both get a view.
When the train drew in, there was a very elderly frail lady sitting in one of their seats I was faced with a dilemma, did I evict this frail lady so that one of my strapping youngsters could take her seat and leave her having to find another one. A guard did say that he could move her, but I didn't feel I could. so DC sat side by side.
Not too big a problem, but I felt that I had been emotionally blackmailed by whoever put this lady on the train, that her frailty would stop whoever had booked and paid for the booking the seat, would feel that to move her would be considered bad form. It still rankles.