Add address custom fields in admin order email

-- HikaShop version -- : 3.0.1
-- Joomla version -- : 3.7.2
-- PHP version -- : 7.0

Hello,

i have created several address custom fields (vat number, job etc) that appear when a user wants invoice instead of receipt.
So, when an order is created and invoice is selected, i want the admin order email to include those custom fields.
How can i do that?

Thank you in advance

Thank you nicolas,

another thing, vat number field is displayed only if the customer selects invoice, so in case the customer selects receipt there is an empty line in the address. Also this () shows up.
I would like to add a title before each address field, how can i do that?

Thank you