How to Only show top parent customers transactions, not all sub customers

We're in the process of creating sub customers for different forms of financing, but all for the same customer. We decided to use sub customers to tie them all together, which works except at the top level parent customer (which is the main customer without any financing option attached) it shows all the sub customers transaction records. Our sales reps would like to only see that parent customers transactions when they are looking at that customer. Support sent us a work around which involves creating a custom sub list and saved search, however you still have to manually select the customer you want