Exclusion of files from "scope"?

Hi,

I am developing several different apps under 1 project tree, namely a frontend and a backend (admin) panel. 

\src\frontend

\src\backend

So both the frontend and the backend app directory trees are under the same \src directory.

The issue I am having is that PHPStorm is cross-referencing files. For example, I have a SASS source for each of the 2 apps but each app can see the other SASS files so they are cross-referencing between the 2 apps.

Is there anything I can do to stop this from happening? I have looked at scopes, but I dont think that solves his actual issue?

Any help greatly appreciated.