丹尼尔·克拉布和我有同样的问题。建立this site 它有一些代码，可以在显示相应帖子的同时查找和使用父类别的模板文件。

我已经更新了它，以支持文件名中的slug（而不仅仅是类别ID）。

// Use a parent category slug if it exists
function child_force_category_template($template) {
    $cat = get_query_var(\'cat\');
    $category = get_category($cat);

    if ( file_exists(TEMPLATEPATH . \'/category-\' . $category->cat_ID . \'.php\') ) {
        $cat_template = TEMPLATEPATH . \'/category-\' . $category ->cat_ID . \'.php\';
    } elseif ( file_exists(TEMPLATEPATH . \'/category-\' . $category->slug . \'.php\') ) {
        $cat_template = TEMPLATEPATH . \'/category-\' . $category ->slug . \'.php\';
    } elseif ( file_exists(TEMPLATEPATH . \'/category-\' . $category->category_parent . \'.php\') ) {
        $cat_template = TEMPLATEPATH . \'/category-\' . $category->category_parent . \'.php\';
    } else {
        // Get Parent Slug
        $cat_parent = get_category($category->category_parent);

        if ( file_exists(TEMPLATEPATH . \'/category-\' . $cat_parent->slug . \'.php\') ) {
            $cat_template = TEMPLATEPATH . \'/category-\' . $cat_parent->slug . \'.php\';
        } else {
            $cat_template = $template;
        }

    }

    return $cat_template;
}
add_action(\'category_template\', \'child_force_category_template\');

实际上是个过滤器挂钩

https://developer.wordpress.org/reference/functions/get_category_template/

/**
 * Retrieve path of category-videos.php template for \'videos\' subcategories
 * Filtered via \'category_template\' hook
 *
 * @param string Full path to category template file.
 *
 * @return string Full path to category template file.
 */
function get_category_videos_template( $template ) {
  $category_ID = intval( get_query_var(\'cat\') );
  $category = get_category( $category_ID );
  $parent_ID = $category->parent;
  $parent_category = get_category( $parent_ID );
  /**
   * Check wheter the $parent_category object is not a WordPress Error and its slug is \'videos\'
   */
  if ( !is_wp_error( $parent_category ) AND $parent_category->slug == \'videos\' ) {
    /**
     * Check if the template file exists
     *
     */
    if ( file_exists( TEMPLATEPATH . \'/category-\' . $parent_category->slug . \'.php\' )) {
      return TEMPLATEPATH . \'/category-\' . $parent_category->slug . \'.php\';
    }
  } else {
    return $template;
  }
}
add_filter( \'category_template\', \'get_category_videos_template\' );