No update of Partial payment in invoice

Hello Experts,

I have a scenario relating partial payments. An invoice is posted of amount 100,000. A partial payment of 20,000 is made against invoice. After partial payment, client cleared the invoice of amount 100,000 and the system allowed it to process. Now partial payment remains in the account. Why the system is not making any link with invoice as partial payment is made against that particular invoice? As per my knowledge, the system should only allow the user to clear invoice by selecting original invoice and the partial payment that was made against this particular invoice.

Please guide me in this matter

Regards,

Atif amin