Ain't gonna work like that. Regular Elven is just 4 standard pieces (armor/helmet/boots/gloves) This stuff is modular with separates for upper and lower body, shoulders and neck. You can load up the upper body piece in Outfit Studio, use 'Add Project' to add lower body, neck part ('Amulet') and shoulder pieces. Maybe also add zap sliders for neck and shoulders. Then use 'save project as' to save with a new output file name, (i.e. armor_0/1.nif), as well as different display name and shape data file. Then build it in bodyslide. After that, one can still do the thing with copying the files around, but it will have one complication: the helmet. You can copy over the circlet.nif to replace helmet_0 and _1, but elven helmet uses both circlet and hair slots, meaning anyone wearing elven helmet will have it look like the crown, but they will also be bald. It would be best to fire up the mod's esp in Creatiuon Kit, and edit the vanilla ArmorAddon and Armor entries for Elven to point to this mod's models.