You can add email programmatically using hooks and filter:
add_filter( 'woocommerce_email_headers', 'mycustom_headers_filter_function', 10, 2);
function mycustom_headers_filter_function( $headers, $object ) {
if ($object == 'customer_completed_order') {
$headers .= 'BCC: My name <my@email.com>' . "\r\n";
}
return $headers;
}https://wordpress.stackexchange.com/questions/92020/adding-a-second-email-address-to-a-completed-order-in-woocommerce
https://quadlayers.com/add-multiple-email-recipients-in-woocommerce/