Wavepad does integrate with Videopad. When appropriate, a right-click on the audio clip may display this 
Wavepad will open the clip. Do your thing, then click the red X at the top-right. The file will replace the original on the timeline in Videopad. This doesn't destroy the original on the PC. If the menu choice doesn't appear simply open Wavepad conventionally to edit the file, then import it into VP.