While possible, you are taking about a major undertaking.
As it is now, the trigger starts a show file. To do what you are talking about, you would have to be able to run two or more show files at the same time, combining both the light and sound data before outputting it. The lighting data might no be too bad, but right now I believe the audio decompression and playback is done in the audio module. I don't know what it's capabilities are, but decompressing and mixing the audio in the pic will add significantly to the code...