Follow the steps below:
- Upload both documents in OkiOki.
- Choose the invoice and follow … take me to the booking.
- In "Documents" choose the “+” icon at the top right and select the credit note.
- Add a comment, e.g. “Invoice and Credit note, without transaction”.
- Then choose “Complete!” and you're all set.
You can find more information on combining multiple documents and multiple transactions in this article.