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.![4 4](https://ogrforum.ogaugerr.com/fileSendAction/fcType/0/fcOid/78579203885315313/filePointer/78579203896906771/fodoid/78579203896906762/imageType/MEDIUM/inlineImage/true/4.jpg)
![5 5](https://ogrforum.ogaugerr.com/fileSendAction/fcType/0/fcOid/78579203885315313/filePointer/78579203896906772/fodoid/78579203896906763/imageType/MEDIUM/inlineImage/true/5.jpg)
![6 6](https://ogrforum.ogaugerr.com/fileSendAction/fcType/0/fcOid/78579203885315313/filePointer/78579203896906773/fodoid/78579203896906764/imageType/MEDIUM/inlineImage/true/6.JPG)
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!)![1 1](https://ogrforum.ogaugerr.com/fileSendAction/fcType/0/fcOid/78579203885315313/filePointer/78579203896906768/fodoid/78579203896906759/imageType/MEDIUM/inlineImage/true/1.JPG)
How 'bout this version of what you had in mind?
FrankM