[Donald Leitch]

If you have After Effects too you can use this trick:

– Copy the contents of your timeline and paste it into an After Effects composition.

– Right click on each media file in the Project pane and select Replace with Precomp.

– Copy the contents of the composition and paste it back into an After Effects Sequence.

– You should now have that precomp as a nested sequence. Enter the sequence that contains your media. Add a new audio track, sync it up and mute the original audio. These changes will reflect in the original sequence.