Replace project with stereo files with Clips with better Mono files

WE just finished a film filmed with a NIKON 750 and an additional Audio recorded for sound.

We did a first cut using the original stereo audio from the Nikon.

We created new MOV files synching the stereo audio with the mono audio from the audio recorder.

We now have a MOV file with only one MOMO Audio track, which we need to use as the sound is perfectly clean while the original Stereo from the Nikon is not usable especially in the exterior scene fro the wind and additional noise.

We removed from the desktop the HD with the various CAMERA CLIP as the new files with the exact same name are in another Drive.

This woild force Premiere to link the files again.

Launcing the project it asked to relocate the files, now converted with the same video specs but with MONO audio instead of the original stereo we used previously, and probably is somewhere inside the project file.

Premiere sequence doesn't allow to replace the original stereo takes with the new audio files giving an error.

Is there any way at all to avoid editing all over again and using the new files with the different (mono) audio track?

We set the audio preferences as "file" hoping it would work but it doesn't

We work with IMAC RETINA 27 64 GB RAM

Premiere pro CC ver 12

The Camera Files: H.264, 1920 × 1080, Millions. Audio from the camera: 16-bit Integer (Little Endian), Stereo, 48,000 kHz

Audio from the external recorder: WAV files 24-bit Integer (Little Endian), Mono, 48,000 kHz

ANy help would be great as we really hope not to edit again

Regards