Ian, that's a rather nice thing to do for your father-in-law. When I reach 87 I hope I'll have a son-in-law like you (maybe I should introduce the idea to my daughter!).
Must require some careful balancing of time and effort to have three locos on the go at once. Let's hope they don't get mixed up. Not sure a "Galloping Bulldog" would go down well with GWR fans .