FIFO based adjustment with Invoices

Hi,

I have attached a sample file which contains a sample data with also the solution that i'm looking for. I have labeled them accordingly depending on the situations as below.

I'm trying for a code/formula wherein the receipt that i receive will be adjusted against the oldest invoice value pending and carry forward to the next invoice if there's any excess receipt and so on. (Case 1)

In case, if the value of receipt is not sufficient to set off with a particular invoice then the remaining amount of invoice will be set off against the next receipt available in sequence in the immediate next line. (Case 2)