Lockbox Application : Discount is getting applied and then adjusting Invoice Amount

Summary:

During Lockbox application process, system is first applying the discount amount first and then adjusting the invoice amount during invoice applications..

For Example: We have an Invoice 123 for 10000$ and Payment Term Discount is 1%; the Receivable amount after discount is 9900

But customer has paid us 9920$ and we have received the same amount in the Lockbox for the invoice 123, system is first applying the discount of 100 and then adjusting the invoice application amount as 9900 leaving 20 as unapplied amount.

Our requirement:
We want the system to apply the actual amount received from the customer ($9,920) to the invoice first, and then adjust the discount to $80, so that the invoice is fully closed and no unapplied amount remains.