AR invoice drawn from deposit or Applying Invoicec to a deposit TWICE

Is there a way to apply one AR invoice to two different deposits (commitment)?

here is the case:

1. customer ABC made 2 deposits with us.      dep-1: 20,000.00 and dep-2: 6000.00

2. Invoiced to customer for goods sold for 22,500.00

3. customer told us to settle the invoice with the full deposit of 20,000.00 and the outstanding amount of 2,500 will be settled through a receipt.

4. After application of the AR invoice to dep-1 reduces the commitment balance to zero and reduces the invoice OS to 2,500.

5. Issue is HERE: after some time customer told us to settle the OS of 2,500 on this invoice  with dep-2 leaving the OS on invoice to Zero and leaving the commitment balance on dep-2 to 3,500.