Company name as Name and customer name as YourReference

functions.php

<?php
/**
 * @snippet       WooCommerce - Fortnox plugin by Redlight Media - Add Company Name to Fortnox order Name
 * @author        Redlight Media AB / Christopher Hedqvist
 * @compatible    WooCommerce 3.3.5
 */
function redlight_fortnox_order_companyname( $orderData, $order_id) {
    $order = new WC_Order($order_id);
    if(!empty($order->get_billing_company())){
        $orderData['Order']['CustomerName']  = $order->get_billing_company();
        $orderData['Order']['YourReference'] = $order->get_billing_first_name()." ";
        $orderData['Order']['YourReference'] .= $order->get_billing_last_name();
    }
    if(!empty($order->get_shipping_company())){
        $orderData['Order']['DeliveryName']  = $order->get_shipping_company();
        $orderData['Order']['YourReference'] = $order->get_shipping_first_name()." ";
        $orderData['Order']['YourReference'] .= $order->get_shipping_last_name();
    }
    return $orderData;
}
add_filter('obj_fortnox_order_data', 'redlight_fortnox_order_companyname', 100, 2 );
/**
 * @snippet       WooCommerce - Fortnox plugin by Redlight Media - Add Company Name to Fortnox customer Name (Registrered users)
 * @author        Redlight Media AB / Christopher Hedqvist
 * @compatible    WooCommerce 3.3.5
 */
function redlight_custom_customerdata_companyname( $customer) {
	 $billing_company = (!empty($_POST['billing_company'])) ? $_POST['billing_company'] : "";
   $billing_first_name = (!empty($_POST['billing_first_name'])) ? $_POST['billing_first_name'] : "";
	 $billing_last_name = (!empty($_POST['billing_last_name'])) ? $_POST['billing_last_name'] : "";
	 $shipping_company = (!empty($_POST['shipping_company'])) ? $_POST['shipping_company'] : "";
	 $shipping_first_name = (!empty($_POST['shipping_first_name'])) ? $_POST['shipping_first_name'] : "";
	 $shipping_last_name = (!empty($_POST['shipping_last_name'])) ? $_POST['shipping_last_name'] : "";
	if(!empty($billing_company)){
        	$customer['Customer']['Name'] = $billing_company;
		$customer['Customer']['YourReference'] = $billing_first_name." ".$billing_last_name;
	}
	if(!empty($shipping_company)){
		$customer['Customer']['DeliveryName'] = $shipping_company;
	}
  

    return $customer;
}
add_filter( 'obj_fortnox_customer_data', 'redlight_custom_customerdata_companyname');
/**
 * @snippet       WooCommerce - Fortnox plugin by Redlight Media - Add Company Name to Fortnox customer Name (Guest users)
 * @author        Redlight Media AB / Christopher Hedqvist
 * @compatible    WooCommerce 3.3.5
 */
function custom_fortnox_guest_customer_data_companyname( $customer, $order_id ) {
	
    $order = new WC_Order($order_id);
    if(!empty($order->get_billing_company())){
        $customer['Customer']['Name']  = $order->get_billing_company();
        $customer['Customer']['YourReference'] = $order->get_billing_first_name()." ";
        $customer['Customer']['YourReference'] .= $order->get_billing_last_name();
    }
    if(!empty($order->get_shipping_company())){
        $customer['Customer']['DeliveryName']  = $order->get_shipping_company();
        $customer['Customer']['YourReference'] = $order->get_shipping_first_name()." ";
        $customer['Customer']['YourReference'] .= $order->get_shipping_last_name();
    }
    return $customer;
}
add_filter( 'obj_fortnox_guest_customer_data', 'custom_fortnox_guest_customer_data_companyname', 10, 2 );