How do I add a second stream to an AVI file in VirtualDub?

[athenian200]

I have a track with music and sound effects included, and I also have a WAV file with my commentary. In VirtualDub, if I go to "Audio from another file," and then select my track, then the resulting video only has my commentary and the original stream is gone. And then when I go back to select Stream 1, the audio comes back and it doesn't play my commentary.

It seems like it's only letting me have one audio stream, but I know AVI files are supposed to support two streams. I would think a program with DUB in the name would be ideal for this, but the process is extremely counter-intuitive. Is there a way to do this, other than trying to extract the audio stream, mix it with my commentary in another program, and then reinsert it? Because I really don't want to do that if I don't have to, and it seems very likely to reduce sound quality.

[sambat]

VirtualDubMod - Streams > Stream list > Add.

[hello_hello]

I think the "single audio track" thing is some sort of early Windows limitation, and VirtualDub still abides by it. VirtualDubMod and AVIMuxGUI don't.