- On Opportunity Product, create a new N:1 Relationship between Account and Opportunity Product
- On Opportunity, under the 1:N Relationships find the the relationship between Opportunity and Opportunity Product, add a new mapping between Opportunity ‘customerid’ and Opportunity Product ‘new_accountid’ (or whatever you called it)
- On your Account form add your sub-grid, now you should be able to select:
- Records: Only Related Records
- Entity: Opportunity Products (Account)
- Default View: All Opportunity Products
The same process should also work for Quote, Order and Invoice Products and well as Contacts. You would just need to create the additional relationships and mappings.
Keep in mind, this does not provide any kind of filtering so if you have the same Product related to multiple Opportunity Products, you will see it listed multiple times.