Can somebody please explain to me how to include more audio tracks in a multicam sequence?

Good evening Adobe friends.

I'm going to try my absolute hardest not to write with the burning passion of wanting to claw my eyes out. It's going to be hard. Bottom line, I don't *for the life of me* understand the infrastructural logic behind Multicam Sequences. It feels like a feature that takes more luck than know-how to succeed with. 

I've created a project, in which I've included three cameras as well as separately recorded audio. Selecting my three camera angles I then created a Multicam Sequence and started chopping away at editing the scenes. I then wanted to open the Multicam Sequence, pop in the right audio track, synchronize it with the cameras, mute the camera audio and export.

Sounds simple, but apparently not? The Multicam Sequence is tied to the sound of Camera 1, which I realize is an option you can specify when you create the multicam sequence. But that HAS to be able to be changed after the Multicam Sequence is created, right!? 

I have another project in which I've (to the best of my ability) done the exact same thing, and it just works. if I add an audio track inside the Multicam Sequence, it plays in a sequence made from the Multicam Sequence. 

I'm so complete and utterly confused.

Help will be greatly appreciated.