Add this code to your child theme’s functions.php file:

function custom_additional_manifest_container_information( $container_id ){
    /*
     * HTML Code here
     * User the variable "$container_id" to get data of the container
     */
}
add_action( 'wpcsc_pdf_before_footer_manifest', 'custom_additional_manifest_container_information', 10, 1 );