I'm not sure if you can. A work round might be to add additional baseboards to the route, use the Copy function to copy the original route to the clip board, use the rotate compass to rotate the route you have just copied to the clip board, then Paste that to the new baseboards. Delete the original baseboards and finally go through the merge process.
I did this with sections copied out of several of my existing routes to create this:
It's a combination of Port Loleta, Deepwater, Krashnburne and IntenCity. I cut out some sections. I had to rotate several sections. Be advised, though, that the TurfFX effects do not survive the Copy and Paste.
I saw a video of 2 routes being merged and 1 route was rotated but was not stated how it was rotated,, or was this and empty route with no assets, https://www.youtube.com/watch?v=A_0V1rSfYvM
Cheers
I just was not sure what was happening on that video when he changed the angle of the route it seemed to changed the direction of the route from his first attempt
Thanks anyway everyone
Cheers