Recently Xeo rolled out this integration and Quaderno state :
"How does Xero integrate with Quaderno? The process couldn’t be simpler. In your Invoices page, you’ll see under the invoices the option to Export to Xero. Just click that link and Quaderno will export an simple CSV file with all your invoices that you can then import into your Xero account."
It would be great if we could do this within Kashflow.