Vat number in Spain:

You could make these changes in the Address fields of Checkout settings:

In the "First name" field you must place "NIF-CIF" (or "NIF-CIF-VAT").
In the "Last name" field you must place "Nombre".
In the "Company" field you must place "Apellidos - Empresa".

This is a big big fudge, but all work fine! and the invoice is almost legal! Thanks.