Do you mean insert an asset you see in another route?
You can do this by opening up the route you see an asset you like in Surveyor.
Choose the Scenery tab for items such as the Steam Filling Station, for example.
Click on the Get asset.
This will display the name of the asset.
Close that route and open your own. And then you open the route in Surveyor, Scenery tab and place that asset if you have Surveyor set to remember the last item selected, which I think is the default anyway.
