Sometimes audio files are too short and does not match the length of the video files
Instead of making another reel with a silent soundtrack you can add some silence to the audio files using Sox.
To make a 48 khz 24 bit 10 second silent wav file with sox:
sox -n -r 48000 -b24 silent10sec.wav trim 0.0 10.0
To add this to the end of another 48 khz 24 bit sound file with sox:
sox film.LFE.wav silent10sec.wav film2.LFE.wav
In Ubuntu Linux you install sox using
sudo apt install sox