How to show additional info in invoice?

[Valdis Vītoliņš]

Another problem for invoice is that I need to show
Reg No, VAT Reg. No and account info,  for current (my) company and
customer/vendor.
There are no explicit fields for this, but I can enter this info in
address field for current company,
and in notes field for customer/vendor.

Though now I stuck finding how to get value for customer notes field,
because I can't see similarities between invoice code and 
http://code.gnucash.org/docs/HEAD/group__Customer.html

So questions are:
1. Is this workaround applicable way, or there are better approaches?
2. Code example how to get Customer/Vendor notes. 

Thanks,
Valdis