Possible to change trackage for a session only?

Possible to change trackage for a session only? (TRS19)

TRS19
Is is possible to change (replace) the track used on a route for a session only? ie: Replace all of track XYZ with track ABC but only for this session. Seems impossible to me since the track is on the route layer but thought I'd ask.

I did some experiments on this years ago when layers first appeared in Trainz. I thought that this would be a great way to recreate a route as it appeared at different times - place the track that existed in 1960, for example, in a session layer for the 1960s session and the track as it existed in 1990 in a session layer for the 1990s session. Alas, the experiment failed as it just it created more problems. Signals, track junctions, anything that was attached to the tracks would not work correctly, particularly (but not exclusively) where the tracks from the two different eras joined together. Trains also got confused over which tracks they should take.

More recent investigations revealed that all track and track objects are best placed in the same route layer.

Thanks... that is what I would have suspected but never hurts to ask.