Need Formula to Calculate Sale Month Back to Production Month

I'm trying to link the sale of our widgets back to the production month.

For example, in my spreadsheet, we produced 401 tonnes in July and sold 293.10 of them in Sept and the remainder in October. I want to allocate the sale and cost on the invoices back to it's production month. All of "Invoice 1" revenue would be allocated to July as it is part of the 401 tonnes produced in July. $15,800 of the 2nd invoice is allocated to July as 107.90 tonnes are part of July's production, the remaining revenue would be allocated to September production month as we had no production in August and produced 933.41 tonnes in September. And so on and so forth...

The cells highlighted in green are data that will be manually entered each month. My spreadsheet is messy so if you want to re-arrange the data to make it make more sense, feel free to do so.

I hope this makes sense and thanks in advance!


Newbie