Hmmm...

1] I'm using WMP ver 10. I can't see "Play->Audio->then choose audio stream "

2] In VLC Audio->Audio Track->choose stream I am only seeing the one track for a single track I'm playing, so that figures! maybe if I had more streams I could select? Is that correct?

OK, my guess, and I've never done this, and speaking of WMP - which I can't see the path you speak of, would be to use Windows Media Encoder (free) and see if there is a way to encode multi audio streams? Dunno.

But now I understand what you want to do and that there appears to be an option to do this, this is very interesting indeed. Never heard of it and never ever used it either. I've looked through the various Vegas WMP options. Nada.

However lurking in amongst the Vegas AVI: Render > AVI > Custom > Audio there are multi "channels". But for the life of me, I can't figure nor make out how to employ them!! ...Interesting . .

This needs more work! Maybe somebody else can jump in.

Grazie