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Theoretically, this can be done in Trainz+ by copying the baseboards and making a clipboard object (I forgot the real name and I don't have TRS22+ loaded to take a look.) of that area. You can create new baseboards at the same height as the area you want to paste on to and then paste down your clip which you can rotate into place. The only routes this can't be done on are the built-in and the DLC routes from N3V. If they are from the DLS or third-party such as Jointed Rail, they will work fine.
Now, with that said, how easy is this to do when managing an unwieldy area like that? Surveyor, no matter what version, gets a bit sluggish when moving huge things into place and pasting down the huge chunks accurately can be challenging but theoretically it can be done.
The old way is to build in between baseboards to connect and blend two differently facing routes. Once the "bridge" portion is created, you merge the routes together and blend the scenery to match. It takes some practice, and the results can be quite convincing when done well.
And finally, there are assets called i-Portals.
An i-Portal is a portal object, as the name implies, that allows the user to send trains to another user or to himself via the internet on the i-Portal server, or via loopback to his own computer. The most difficult aspect of this, which really isn't is placing the portal where you want and setting up the to-from names. When configured, a train is sent to an i-Portal just as any train would be directed to a portal or other industry/station asset. The disadvantage of these is the trains go to the Ether and don't load on the other route until the route's session is opened in Driver where the trains are sent from the portals after a set amount of time that you specify.
Currently, I've been using i-Portals to connect many large routes including those of my own that I always wanted to merge but couldn't either due to their size, baseboard height, or direction. They do work as advertised and when the freight consists arrive from another route, they retain their commodities. You are then required to insert the driver's schedule to allow the train to continue manually, or you can just let the consist drive along without any control over it. I prefer the manual control because my trains enter a yard where I switch out the freight cars.