My DB wants my 82-year-old DF to visit him and his family (BIL and 3 teen DCs) for tea. My DF would love to go, of course. However, DB lives about 50 miles away. He has asked that my DF get the train (involving a taxi to the station and a 90-minute journey with one change, as well as the price of the ticket), but surely it would be better for them to get in the car and travel to have tea with DF? If it was an overnight or even a full day visit I'd not be so bothered, but a >3 hours' journey for an 82-y-o seems a bit much for a fairly short visit.
For avoidance of dripfeed, DF is fairly fit and mobile but tires easily and has days when he "feels his age". 2nd DC has some additional needs but these do not impact on ability to travel.
I get that hauling 5 people out is a faff, but is it less inconvenient than expecting DF to get the train?