Adding a custom billing email field

Thanks for this wonderfull plugin!

I had the problem, that I use a custom field in the checkout where users can enter an additional e-mail address for their billing departement. Problem was, that I wasn’t aware that it needs to start with billing_ and that it didn’t show up in the users profile after creating or syncing the profil within a order. Chat GPT hepled me to create the following script and it seems to work. I thought I post it in case others are struggling as well. Hope it is correct otherwise please correct! 😉

/**
 * Add custom billing field to the order edit screen and user profile in backend.
 */

add_filter('woocommerce_admin_billing_fields', 'order_admin_custom_fields');
function order_admin_custom_fields($fields)
{
    global $the_order;

    $fields['invoice_email'] = array(
        'label' => __( 'Invoice Email', 'woocommerce' ),
        'show'  => true, // shows field in the order billing box
    );

    return $fields;
}

add_filter('woocommerce_customer_meta_fields', function($fields) {
    if ( isset($fields['billing']['fields']) ) {
        $fields['billing']['fields']['billing_invoice_email'] = array(
            'label'       => __('Invoice Email', 'woocommerce'),
            'description' => __('Additional email address for invoices', 'woocommerce'),
            'type'        => 'email',
            'custom'      => true,
        );
    }
    return $fields;
});

Best regards, Fletsch