Position Heirarchy setup

Hi All,

We need to update the Purchase Order Approval Limit for Inventory & Expenses PO’s as below.

For Inventory Orders –  Orders above 2000 INR need to be routed to "A" for approval.
                                          Orders above 5000 AUD need to be routed to "B" for approval.
Rest of the order hierarchy to be kept same.

For Expense Orders - Buyer Approval Limit needs to be set to 1000 INR.
                                     Orders above 1000 INR need to be routed to "A" for approval.
                                      Orders above 2000 AUD need to be routed to "B" for approval.

Rest of the order hierarchy to be kept same.

how  to identify the segregation criteria for expense and inventory orders.