Reconciling Large Amount Of Data When VLookup And Match / Index Not Ideal

I need a little coaching on big data. I have two reports, one from a production system the other from the invoicing system. I need to reconcile the two reports to ensure our invoicing ties out to production. At this time I am focusing on 1 particular item code, but there are potentially hundreds of item codes.

I have 1 Item Code.
I have a around a hundred invoices. (Sample 100)
I have a few hundred different customers. (Sample 100)
I have several hundred lines of billing data. (Sample 650)
I have several thousand lines of production data. (Sample 40,000)
In the billing system, per invoice I might have 1 or more billing lines for this item, usually no more than 2.
In the production system, per invoice I might have 5 to 50 or more production lines for this item per invoice.

Example
Prod System:
30 lines of data has a run amount and a total run amount for each line.

I am looking for tools to reconcile this data. VLookup and Index/Matching is not cutting it. VLOOKUP does not move beyond the first line found. Index/Matching wants to add all the prod together. I can get subtotals easy enough. I have tried Concatenation, but when it takes multiple production data lines to equal 1 billing line, this does not work. I needs some thing that can look at the Qty on a billing invoice and tie it out to various lines of production data to identify which production jobs went on that line of the invoice.

Here is a sample. These are fairly easy to resolve, but others are not so easy due to number of production and billing rows.

Invoice number
Billing item
Est. Quantity
Actual quantity
Billable Qty
Sales order
Position number
Sequence
Agreement
Billing source
Description
Total Billable Qty

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