Run generate_template_from_base.py to make a template
Run map_cats to map most selection entry links along with the groups for warlord traits and retinues
Some selection entry links that have multiple entries with the same name and hidden value may need to be manually mapped. map_cats will list the names of all entry links which need this.
For a first run, use copy_overwriting_all_modifiers.
For a follow-up use copy_changes_from_template.
list_legion_changes can show any differences between a source and target file