How to set "file output," node directory from command line?

In my .blend file i have multiple scenes who’s render outputs I need combined into a single multilayer EXR

I am using my render farm, so I need to be able to specify the output directory like so “blender -b myFile.blend -o myOutputDir\filename_ -a”

If I do this using a multilayer EXR, then the only thing that actually gets output to that directory are the layers from the main scene I am rendering, and not the second scene I have plugged into the file output. The actual file output node will just render to whatever path was set in the GUI.

I have attached an example file of what I am trying to do. Is this possible at all?
outTest.blend (552.5 KB)