POP Order Authorisation by Department rather than based on Order Originator

We require multi level authorisation of our orders. This would be ideal if completed in the requisition stage as this follows the department to avoid the work of creating a later denied order, but this does not allow any approval levels set by the value. The solution we are using is to set the department budget holder as the Order Originator to allow an order to follow the line management route for a department and gain approval from those required dependant on value. The downside of this is that the order originator can only be set by manually amending the order after it has been created. A good solution would be the ability to have orders authorise based on value and use the department rather than order originator to follow a sign off structure which would take out this step.