Custom Report - Sales order fulfilment vs invoice quantity

Hi there, 

One of our clients has a need to see the sales order quantity fulfilled for each fulfillment vs the invoice is was raised or allocated against?

If core allows one on the invoice tab to refer what fulfillment they are invoicing why isn't there a report that can provide that outcome. Thus showing that fulfilment one is related to invoice 1 and this is the quantity used. Instead the fulfilment report groups of the invoices regardless of the fulfilment number. 

This is quite frustrating especially because the data is there to be able to formulate such a report in Cin7 without having to combine various reports in Excel to get that information.