Trouble Calculating Sum / Countrow

Hello All,

   Having trouble wrapping my head around how to get the number I'm looking for here. Here's the scenario (note I thought about posting some sanitized data to help, but it's millions of rows, multi tables....so I hope my explanation here suffices).

First, the relationships:

Label is related to the mrProducts table on a many-to-one relationship.  (Labels * : 1 mrProducts)

OrderItems table is the sales table, related to mrProducts on a many-to-one relationship (OrderItems * : 1 mrProducts)

OrderItems relates to Campaigns as many-to-one (OrderItems * : 1 Campaigns)

Campaigns relates to Blocks as one-to-many (Campaigns 1 : * Blocks)

Blocks relates to Codes as one-to-many (Blocks 1 : * Codes)

We issue codes used to validate against a product sale. Many codes are issued, only a percentage are redeemed. I'd like to figure out how many codes - on a per label basis - are issued (and from there I can figure out the percentage). The report canvas has a slicer with Labels. Selecting that label shows all the sales no problem, but trying to establish how many codes were issued per campaign is where I get stuck.  The Codes table has all codes that are issued.  Essentially, I need to count the number of rows in Codes that are related to any of the products within the Label found set.  That's a very circuitous route:  Codes -> Blocks -> Campaigns -> OrderItems -> mrProducts -> Label.

Any thoughts? Is it possible? Let me know if I can further simplify this explanation.