add_rewrite_rule() not playing nice with child pages

function my_add_rewrite_rules() { add_rewrite_rule('testing/([^/]+)?$', 'index.php?pagename=testing&event_slug=$matches[1]', 'top' ); } add_action( 'init', 'my_add_rewrite_rules' ); function add_query_vars( $query_vars ) { $query_vars[] = 'event_slug'; return $query_vars; } add_filter( 'query_vars', 'add_query_vars' ); /testing/foo – Works, shows foo If I have testing set to no parent, the rewrite works and everything is good to go. If I set testing to a … Read more