Alright, I came here looking how to solve it and actually figured out your answer: First off, make sure that everything under weight matches your armor class (This is just for prudence.) Then under Keywords, Editor ID, right click and Copy Stack from whatever armor piece you are using as a BASE for your modded armor. Then go to your modded item, delete everything under Editor ID, right click and Paste Stack. Repeat this until each piece in your set matches the pieces they're based on. This SHOULD trigger the matching set as long as the Materials match on top of everything else.
