Used this method to move the billing address form prior to the shipping address form, but it is not fully functional.
The billing address updates on the Update button press - OK.
Internal form validation works, error is shown if the Update is pressed while it is empty - OK.
The billing address is not validated, if the Next button is pressed - not OK.
The billing address can be absolutely empty, but pressing the Next button makes the browser proceed onto the next stage.
