Imported scenes will show up just as any other Scene in the DISE Movie, but the difference is that the actual scene resides in another file. This means that you can import the same scene in several places in a DISE Movie.
Editing external scenes
If you edit the external scene file, the same changes will apply to all the imported scenes.
If the Save changes back to the external file option is enabled, any changes to the imported scene will saved to the external file. Otherwise they will be discarded when you close the DISE Movie.
The easiest way to edit external scenes is to have an extra DISE Movie where you import all the external scenes, and edit them. And in the main DISE Movies you import the scenes anywhere you want without using the Save changes... option.
Multiple imported scenes
If you have a number of scenes that you wish to import, use a content pool. This will dynamically generate the scene from a list of scenes or files. For every time the scene using the content pool will be displayed, a new scene from the content pool will be used.