Filtering through Layers of Sound with Control Variable

Hi,

I'm pretty new to Max, but I am very determined to create a system in which a single variable, such as the average brightness of a video stream, controls filtering between multiple layers of sound. The most similar post in the forum I found was: https://cycling74.com/forums/maxmsp-controlled-layering-of-4-sounds-dead-space

One key difference between the system described and what I want to build is that different sound clips become available and unavailable as time goes on. I have included a visual representation of the system I was hoping to build.
I would highly appreciate any guidance and or recommendations of tools I could use.