You could try using a level template for that.
- Go to the root templates panel and select the "create new" icon.
- From the "2) Select Type" drop down menu, choose "Level Template"
- Under "3) Properties" and the "Misc->Level Name" category, select the level you want to import from the drop down menu.
- Under the "4) Name" property, give your level template a name. This is the name that will appear in the root template list of level templates.
- Use the "Place New Object" Mode like you would for other objects in a level to add your new level template to the level.
The neat thing about level templates is that you can now go back and edit the original level that produced the template and your changes should be reflected back in the other levels that make use of it as a template. This can really improve design performance within big levels that are comprised of several terrains. Instead of loading the entire level with all the terrains, you can use level templates and work on the individual pieces as desired.
In the levels where you added the level template, you will notice that it appears as a single blob. You can't edit the individual pieces that comprise the template by default. You can either edit the original level or choose to 'explode' the level template in the level where it is being used. You do this by right mouse clicking the level template and choose "Explode Level". This will essentially create a full local copy of the level from which the level template was made. The consequence of doing so is that changes made in the original level file will no longer be reflected in the exploded level template. Larian's workflow was typically to do this at the end once that level was "done".
Good luck!