you right click the inkling/octoling click "add overide materials" then right click again and hover over "show in element veiwer" and click model. there should be a material bar at the bottem and click the little "+" next to it. scroll down to inkling/octoling_underwear. right click and click "add attribute" and go up to an attribute that says "string" and where it says "newAttribute" highlight and get rid of that and type in " $basetexture " and hit enter. the underwear will look messed up (thats normal) and press the "+" next to inkling/octoling_underwear and on the other side there should be an empty space where you paste the undere wear you want