Add Vat nr and company name in the client registration form

-- HikaShop version -- : 3.4.0
-- Joomla version -- : 3.8.6
-- PHP version -- : 7
-- Browser(s) name and version -- : Chrome

I whish to add Vat nr and company name in the client registration form.
How to?

That's it.
Thanks

But they don't appear on the invoice?

Kind regards,

Veerman