= 4.6 provides easy to use functions for that). if (function_exists('get_sites') && function_exists('get_current_network_id')) { $site_ids = get_sites(array( 'fields' => 'ids', 'network_id' => get_current_network_id() )); } else { $site_ids = $wpdb->get_col( "SELECT blog_id FROM $wpdb->blogs WHERE site_id = $wpdb->siteid;" ); } // Install the plugin for all these sites. foreach ($site_ids as $site_id) { switch_to_blog($site_id); self::migrate(); restore_current_blog(); } } else { self::migrate(); } } public static function migrate() { foreach (static::$migrators as $class) { $class::migrate(); } } }