Maya Publish scene script location

Inside tk_config_squeeze

tk_config_squeeze/hooks/tk-multi-publish2/maya.basic/primary.py

In this file you have the set of sg_desc_field, sg_scene_variations and other linked sg_field

Upstream published files

For scene references, it's also in this same file, upstream re pushed using sgtk.util.register_publish with the dependency_paths, so don't search 'upstream_published_files' instead search 'dependency_paths' usage to find, or update upstream.