Hi Wayne, for this type of scenario, we definitely do support instances where the customer's invoices must always go to the head office which is a different address than the sub-office.
On the contact card, under the Terms Tab, the Invoice To field is used for the following:
If a Contact is a Customer who will not be paying your Invoices themselves but may, for example, be purchasing through a leasing company, enter the Contact Number of that company here (that company must also be a Customer or a Supplier in the Contact register).
When you raise Sales Invoices for the Customer from Sales Orders, they will be made out to the company specified here.
This, of course is different to the Delivery Addresses setting in Sales Orders module. To get the proper address to show you will have to choose a form field from that Delivery Addresses Register.
Please ensure that you choose the right field on the forms that correspond to these instances. I hope this helps. Thanks!
HW Support