Post Invoice total amount variance into specific accounts

Hi

We have requirements where if there is invoice total amount variance between PO and invoice, the variance should be posted to specific accounts.

The logic what user wants is same like IPV, where if there is variance in unit price, then post it to IPV account. But now instead of price, we want to have quantity variance or total invoice amount variance to be posted to specific account.

For example:

PO#: PO1 - Qty: 5 - Price: 100 - Total Amount: 500

Invoice#: INV1 - Qty: 7 - Price: 100 - Total Amount: 700

Expected accounting entries

Expense (DR): 500

Variance account (CR): -200

Liability (CR): 700