Hi JUSHAVNFUN, Interesting topic. Here's my version, "Same Layout, different trains" (!)
I do a version of what you suggest by your question. I have locomotives and passenger consists of railroads from Pittsburgh to the Northeast, especially the Pennsylvania RR. I have, also, bought locomotives and passenger consists for the Union Pacific Railroad.
I run the PRR for a time; then, I remove every one of them and replace them with Union Pacific trains.
Seen here, the engine servicing yard is a place on the layout where some of them can be captured together at the same moment on their way thru (posing, of course!)
How 'bout this version of what you had in mind?
FrankM