Assiging part of a payement to previous period debtor control account

I have recently set up quick file for an existing company starting with the end trial balances from my accountant.

When I received payment for invoices from the last period I assign this to the debtor control account Vat etc has already been taken care of in the old system and includes these late paid invoices.

This seems to balance fine except I have one customer who under paid and then over paid including payment for the invoices from the current period. How can I assign this payment part to the debtor control account part to the current period invoice?
Would it be very bad practice to modify the bank entry so the payment is split into parts?
Thanks for your help in advance and am really liking Quickfile.

Kind Regards
Paul

No, that’s fine as long as the overall total is still correct, and it’s probably the simplest way to deal with it (there are other ways involving a separate “holding” bank account but for a one-off like this that’s probably not worth the hassle).