Substitute for Multiply node? I have two render layers.




I am trying to layer one over the other so it creates an inverted effect through the computer monitor.



If you haven't noticed already, my current problem is that the black silhouettes of the character outside of the monitor in the latter render layer cover up the freestyle lines of the characters in the former layer.

Here is my current node setup:



The problem is this node in particular:



The Multiply node only replaces any pixels found in the black area of the alpha mask with more black pixels. I want my nodes to erase all pixels found in the black area of my alpha mask instead.

I will have to use something other than the Multiply node since it currently looks impossible to customize it so it does what I want it to do. 

What nodes can I use instead of a Multiply to fix my issue?

EDIT: Here's the .blend:
Keying Node

In this particular case I would use the Keying node to mask out the inverted image. 



It will allow you to get the area with the key-color you picked.

.

Then you just have to overlay the second layer after running the Chroma key filter as you already did.