PayPal Import - Assign Transactions

When you import data from a bank feed, you can assign each transaction to existing invoices and purchases.  However, for some reason, when you use the Kashflow PayPal import, there is not this option and you can only create new invoices / purchases

Surely you should be able to easily assign the transactions to existing invoices and purchases!  That would certainly be easier than having to enter the transactions manually where the invoices / purchase notes already exist!