F-curves and multiple sounds for lip syncing

Hello, I followed this quick tutorial http://www.youtube.com/watch?v=z-cJ-Jc460M

to make a lip sync for my character for a school project but I ran into some problems namely with multiple sounds.

How I have it set up is that there are two seperate sound files, the voice syncs with the first one but when I want the voice to sync with the second, it erases the first modifier. Any help on how to fix this?

Didn’t watch the video, but my first thought is that if you have it working for one sound file, why not just use 1 sound file? Combine the two sound files into one…