I love doing the official timetables and scenarios, and after spending money on extra locos, it would be nice to be able to use them a lot more! Why not have the two realistic locos for the route as the first options, then be able to select any loco you like? I don't see why I can't instantly run a GWR Class 150 on the West Cornwall route, or the West Cornwall trains on the Riviera line and vice versa. I don't normally have a lot of time to play or spend making routes, so to be able to just fire up a scenario with a different loco would be amazing! I think generally all trains from the said country should be available for all it's lines at least, and maybe an "Off the Rails" button below all country appropriate locos!
Excellent idea, it would mean any train could sub into any service, it would be a really fun addition
This is something I've advocated for. Want to change your Class 390 on Trent Valley for a Class 86 and Load 10, or the 802 on Riviera for a MML HST - should be possible, so long as it fits within the constraints of the original consist. Another example would be a Class 700 in lieu of an Electrostar on BML.