Could use a third include tag. an 'include_absolute'?

I don’t see how though.
Collections can help organize text/html files into different directories/collections but any file I want to include in files from different collections/directories, would still have to exist at multiple locations.

_
  |-- fruits.md          # this,
  |-- red-things.html    # this,
  |-- round-things.md    # and this file can {% include_relative svg/apple.svg %}
  |-- svg /
         |-- apple.svg
         |-- fire-hydrant.svg
         |-- tennis-ball.svg
  |-- other /      
         |-- somePage.md       # but
  |-- directories /  
         |-- someOtherPage.md   # these
  |-- _collectionOne /  
         |-- yetAnotherPage.md   # three files, **can't** {% include_relative ../svg/apple.svg %}
  |-- _collectionTwo /  
         |-- yetAgain.md   # to use {% include_relative apple.svg %} here, I'd need a
         |-- apple.svg    # duplicate
|-- _includes/
         |-- svg/
                |-- apple.svg   # any file, anywhere, 
                |-- fire-hydrant.svg  # could {% include svg/apple.svg %}, but 
                |-- tennis-ball.svg  # since files in _includes don't make it to _site, 
                |-- tomato.svg  # can not have <img src="_includes/svg/apple.svg>