I'm hoping to find a solution where I can link Opportunity Products to Opportunity Splits using a junction object.

The client has revenue quotas for each of their Sales Reps. Then there are two "Specialty Reps" selling specialty items - they assist the main Sales Rep on a sale. These Specialty Reps never own the opportunity, only Sales Reps own opportunities. The Specialty Rep is specified for each Opportunity using a custom lookup field on the Opportunity (this is populated using automation and works great).

The Specialty Reps each have a quota. I need to "give credit" to the Specialty Rep for the sum of Total Price of their specialty items when they are added to an Opportunity as Opportunity Products. This needs to be related to their quota so that a "quota vs actual" report can be created. It is very important that the dollar amount of their "credit" matches the Total Price of the specialty items on Opportunities.

They also like to group their "quota vs actual" reports by product family to see the distribution of products being sold (though, there is no quota per product family). They are also filtering down the data to 5 specific product families. This requires reporting at the Opportunity Product level. I have been using a "Forecasting Quotas w/wo Forecasting Items w/wo Opportunities w/wo Opportunity Products" custom report type to accomplish this after setting up the Opportunity Revenue forecast type.

I tried setting up Opportunity Teams with Opportunity Splits, then enabled the Split Revenue and Overlay Revenue forecast types and moved all the quotas over respectively. I set up automation to create an Opportunity Team Member and Opportunity Split record for the Specialty Rep in the desired scenarios - when a Specialty Item is added, edited, or removed from the Opportunity. The Split Amount is calculated based on a percentage of the Opportunity Amount, and the percentage field on Opportunity Split only allows for 2 decimal places, so this amount gets rounded off which causes a discrepancy in most scenarios. I swapped this out for a couple custom currency fields on the Opportunity Split object where I can set the amounts using automation and a formula field. Even with all this, we would have to sacrifice the Product Family grouping/filtering, since I'd have to use a "Forecasting Quotas w/wo Forecasting Items w/wo Opportunity Splits" custom report type. Bummer.

I'd really like a way to create a custom report type that links Opportunity Splits to Opportunity Products. I tried creating a lookup field that referenced Opportunity Split via API, but it is not allowed. A new junction object called "Opportunity Product Split" would do the trick. I'd be happy to facilitate the data with automation if the architecture allowed for this. I'd always create an Opportunity Product Split record for the Opportunity Owner when each Opportunity Product record is created, then conditionally create an Opportunity Product Split record for the Specialty Rep as desired.

Any thoughts on something I might be missing here? @Mike Wey 

P.S. I've upvoted all the ideas I found related to Opportunity Product Splits and Split Amount calculations