Data segregation within an operating unit

My organisation consists of many subsidiary companies under one group company. 

Our Oracle system set up has one operating unit with all of these subsidiary companies sitting within it, each with their own company code to separate the accounting. 

There is now a requirement to prevent one company viewing another company's data. 

Within General Ledger, I have separated companies by setting up different responsibilities and applying security rules on the company value set which works well. 

When I tried the same method with Receivables, the input was restricted but viewing of the data was not. A restricted responsibility could view the invoices of all companies.