How to secure data of a single vendor

Hi,

my client currently uses R12.1.3 core financials, projects, SCM and eAM products and entered in a joint venture (JV) partnership 12 months ago. As part of the contract all transactional data of their JV partner is too be secured in e-bus so it is only accessible to very few key personnel. Currently my client has a basic structure; one ledger one Operating unit which means whether in payables, projects, purchasing all transactional data ifor JV partner is accesible to all users i.e. invoices, receipts in expenditure inquiry form. Due to tight timeframes we are interested in understanding other options to secure