“wpcfe_invoice_site_info” action hooks that allow to add additional information in the invoice template site information section.
Note: This is available only in the Frontend Manager addon plugin.

Copy and paste this code to the theme functions.php file for sample code.
// In this sample code it will add address to the site infornation.
function my_custom_data(){
?>
<p>Address : Robert Robertson, 1234 NW Bobcat Lane, St. Robert, MO 65584-5678.</p>
<?php
}
add_action('wpcfe_invoice_site_info', 'my_custom_data');