Updating Position Hierarchy automatically

Greetings,

    I am looking to automate the update to the position hierarchy used today to approve purchase orders and requisitions. Currently, much time and effort is spent on updating the hierarchy and mistakes are made along the way. Our position KFF is made up from organization, job, and serial number. We are thinking to include the grade in the mix for the position KFF. Anyhow, the most important thing is that employees are assigned a position, be it available or created, and placed in the hierarchy. Could you advise on how to go about doing so? if you know of