How to replace Mono WAV files in a Poly WAV source

Hello!

I am working with a single Poly WAV audio file that contains 5 mono tracks for 5 different mics. The Poly WAV was synced with the video footage and I cut the video together. Unfortunately there was a lot of interference on the mics so we sent the original Poly WAV file out to the mixer to clean up. The intent was that he would clean them up and send me back one Poly WAV, which would retain the same file name and length, and I could simply replace the original Poly WAV with the new cleaned up Poly WAV. 

Unfortunately the mixer was not able to send back a Poly WAV but instead sent back 5 individual Mono WAV files (for each mic). So, I am not able to simple drag, drop and replace the original file.

My question is if there is a way to -- within FCPX -- replace/relink the 5 Mono tracks within the Poly file to the 5 new "cleaned up" Mono files that I was given from the sound mixer?

Admittedly I mostly edit music videos and have very little sound experience so a lot of what I've been reading online is going over my head. But also, I have not found any articles that directly address this situation so I'm looking for any and all help. Just give it to me in Layman's Terms, please  

Thank you in advance for your time!!
NICK

Hi Nick, welcome to the forum.

You (or your sound guy) can use Audacity or Wave Agent to combine the mono WAV files to a poly WAV. Both are free.

Audacity:  www.audacityteam.org
Wave Agent:  www.sounddevices.com/product/wave-agent-software/

- Ronny