Purchase Ledger Payment Runs ignore cash refunds on account

At present when you generate a payment run on purchase ledger it excludes any cash on account and it doesn't give you the option to add them in. These should be included on the payment run as sometimes they need to be paid and currently you can only deduct them from an invoice which means that you lose visibility of the transaction on the remittance. It is easy to miss these and need to then make manual payments