The children are terms. First register your taxonomies (news, stories, videos), then register travel, people, and nature as terms under stories.
Like so: http://codex.wordpress.org/Function_Reference/wp_insert_term
The children are terms. First register your taxonomies (news, stories, videos), then register travel, people, and nature as terms under stories.
Like so: http://codex.wordpress.org/Function_Reference/wp_insert_term