Change approval hierarki

Dear Oracle Community,

I've change position , Job and hierarchy while there's still outstanding Requisition must be approve.

Let say Employee B  has resign, so filled end date and delete his position and Job on assignment tab on Employee Form.

For the Substitute let say employee C  is Employee B position and Job.

I also change Employee B with Employee C on Position hierarchy.

But When I check the requisition approval notification, the approval workflow doesn't change.  It still goes to Employee B Although I've submit fill employee hierarchy.

Anyone know how to change Approval workflow to new Employee without cancel or reject the requisition?