If you record two mono tracks-- one from a shotgun mic, one from the in-camera mic-- and you want to use the mono track on the shotgun mic for both left and right channels, what is the best way to do that without compromising any Fairlight adjustments you might want to do later?
A mono track will still be played in both the left and right channels, unless the file itself is stereo with one empty channel. You can just right click the track in the tracklist in the edit page to change the track type to Mono.
It's the audio recorded on the camera's built-in mic. (I'm presuming you don't want to hear that at all.)
So in Clip Attributes, you can delete that channel and when you add the clip to a timeline, the Nat sound won't be there. (The actual media file on the hard drive isn't changed. Clip Attributes only tells Resolve how to treat the file in that project.)