When assigning a batch payment, I would like to be able to see part paid invoices listed so that I can clear the remaining balance. It seems a bit obvious and therefore I can't understand why it isn't already possible. Similarly, when a batch payment leaves an invoice part paid, it should be possible to assign it to the fully paid invoices and then assign the balance to the part paid invoice.
This should already be possible - please contact Support@KashFlow.com who can arrange to help you with this.