It would be easier to answer with a link to the scene you mention.
Without this, I can only say that you can load the subscenes from an empty scene (add a "SubScene" atom & go to its "SubScene" tab to load the desired subscene from the VAR package of the scene).
Depending on the subscene, it might not be enough (it may rely on other elements that are included in the scene, not in the subscene, such as a main environment. Maybe that doesn't make sense if the subscene doesn't include the main protagonists.
You could also edit the subscenes to remove any unnecessary atoms. And you'll need to edit the scene to make it load your edited subscenes instead of the original ones.
But that is starting to be complex and time-consuming for just one scene, which won't be anymore as the author intended.