John
/includes/modules/YOUR CUSTOM TEMPLATE FOLDER/additional_images.php

I personally added in case at

/includes/modules/additional_images.php

May be an extra file but did not hurt my page

But worked for me
could not and do not have the time to rename all the files at this moment 963 pictures is not fun

Hope it works

This file replaces the orignal file form the cotribution and this is the only one I have changed

And I removed first and the installed this one. Did not overwrite it
Sincerely
Marcelo