Approving Editors in 6.7.1 SP1 (Windows 2003)

System

We currently are utilizing TS 6.5 on Windows and are in the process of migrating to 6.7.1 SP1 on Windows. I have a question on the setup of approvers in Teamsite for 6.7.1.

Today we set our approvers on the workarea and not the branch. Does this need to change in 6.7.1 and creating a role on the branch for users to approve content? If so how do you restrict what approver can approve in the different workareas.

An example of our store

Branch 1
WA1
WA2
WA3
Branch 2
WA 1
WA 2

We are setting up a role in branch1 and Branch2 to grant access. But our workareas we need approvers to be different across each workarea. In the example Branch 1 (wa1) would have approver A and would be able to approve content in Branch 1 (WA1) but not anywhere else.

Is this possible?