ok...
I would try this. (done from my imagination, so i might have forgotten a step or two)
1. Create 10 seconds of silence and save it in your media folder.
2. Find a piece of video longer than the longest sound-clip and copy it to 3 tracks.
3. Add the silence in front of all 3 video-clips.
4. Un-link the original sound from all 3 videos and replace it with each of your own sound-clips.
5. Move the videos back, and align them with the start of the silence tracks
6. Link silence + your sound to each video.
7. Save all videos under the same name as name1 name2 name3.
8. Open the multi-cam plugin in Powerdirector and load your sound-videos in 3 tracks
9. Ask the program to auto sync your videos.
10. Cut of the silent start of all 3 videos, using one cut. This will leave a short silence on two of the videos, that start later.
11 Un-link the sound from all videos and save them under your own name.
When you use then, just align the start and all should be good. :
Anders