First, Sorry to spam your question, but there are so many things that can be done and my mind is moving faster than I can type.
Second, I’m going to go out into the weeds with this but stick with me, because I think this will work for your OCD. Instead of multiple UV Maps this technique uses multiple textures referred to as tiles. The setup. Select Melvin tab into edit mode. Then in UV Editor create an image. On the N-panel->Image Tab->Image panel->Change source(where it says generated) to UDIM Tiles. Scroll down to UDIM Tiles panel. click the Plus sign. Now you will see the 2 tiles in the UV Editor. Now you can put the eyes on one tile and the body on another. If you want to use existing images they will have to have the same name then period Tile number period file extention(jpg, png, etc). For example a name like test would be test.1001.png and test.1002.png Then set the source to the first image Blender will detect the others. The image source is under where you changed it to UDIM Tiles. To add to your material just use an image texture node. When you select the first image blender should detect that it’s UDIM. If it doesn’t just click where it says Single image and change it to UDIM.
