Invoices discounted to zero

SOLVED

Hi all,

I would like to record interactions with clients where pro-bono services are supplied, including invoicing so the client has proof of service. I approached this by creating a quote for normal rates, then discounting at 100%. Creating an invoice from that works right up to the point where the software baulks at creating an invoice for zero currency.

Is there a better approach I can use to achieve this end?

 cheers

   --oh