Approval group is not working when there is a change in HR record

Organization Name (Required - If you are an Oracle Partner, please provide the organization you are logging the idea on behalf of):

Pilbara Port Authority

Description (Required):

When we implement workflow using approval group, we notice the workflow will not working for user if their employee record have updated. The only work around is to remove the user from the approval group and then add it back to approval group. It is difficult for consultant or adminstrator to relate this issue to the workflow error. I think this issue happen 3 to 4 years ago when I do the implementation. Is there a way (e.g. a ESS job to sync the person in the approval group again when HR record change.