How to Use OpenIV to Match .ymt files with its corresponding .ytd files for a Horse Overhaul Mod?

I know this sounds dumb, but hear me out.

I found a Horse Overhaul Mod that I absolutely love, but I only want to use a few of the coats within the mod. The Mod Creator has stated that they won't tell which .ymt files match to their corresponding .ytd files for individual coats, and that the mod is supposed to be used as an overhaul (You can change every horse in Story Mode, but not specific horses alone).

How do you use OpenIV to match a .ymt file with the .ytd file (the horse file that the modded coat will be replacing)?

Help urgently needed before I pull all of my hair out