Sorry, we were closed for the U.S. Holiday. No you can mix and combine several tracks. If you looked at the article, it should describe how you can add multiple audio tracks for one video as an example. We have customers that add multiple audio language tracks for one video just to give you an idea.
You can also combine them using FF-MPEG and mix them there before you send it to Wowza as you can see described in this post:
One last option for you in addition to the AVmix module is you can have the player select the audio track from a SMIL file. Not sure what your use case is, but I’ll share this in case it’s helpful: