[Swftools-common] replacing sound in a swf?

[Bill Hall]

Is it possible to replace the sound in a swf using swftools?   I tried to use wav2swf then swfcombine -T vid.swf aud.swf   but the output swf has both sound streams.  
We are trying to  replace the English narration track with a German translation in this example.

I had hoped there was some trick I  could do with swftools to delete or replace the original sound track.  If swftools won't do it....is there any other tool that can do the replacement with a swf  (the original FLA and AVI aren't available...)

Thanks!
Bill