restrict employees list of values by ledger across iproc, PO, PA etc

Dear experts,

We are currently using Oracle R12.2.6.  

We don't have full HR, but setup employees through the Purchasing->Enter Employee screens.  There is a Purchasing super user responsibility for each Ledger, and the HR: Business Group is assigned accordingly.   In the Enter Employees screen we default the ledger and common BG what ever ledger an employee belongs to, and also set the default Accounting information for expenses.

We have employees defined against two ledgers but both belobgs to a common Business group.

Now we want to restrict employees list of values across different application where ever employee / buyer / employee-supplier etc dropdown available, to be specific to that BG we have accessed to.