Customer custom field

I have a question regarding Customer custom fields;
Isn’t it possible to add a Customer custom field on a sale invoice.
For example i would need to add the nationality and the tel number of a customer to be printed on a sale invoice, so i have created customer field for these informations, but i haven’t found the way to make them appear on sale invoice printing.
(the only way i have found is to write all the information in customer address field, but it is not satisfactory)
I think customer information is close linked to sale invoice, and perhaps could it be considered as a future improvement to make them available on sale invoice.

The same for suppliers and purchase invoices…

Read the Guide: Use custom fields | Manager. Place the custom field on sales invoices.