Supplier Approvals/Sign for PO

We currently have four levels of PO approvals. Before Level 4 approval, the Supplier must sign the PO, after which it proceeds to the Level 4 internal approval.

We would like to understand the correct solution for achieving this requirement when using both Position Hierarchy and AME approvals.

Scenario 1: Position Hierarchy

• We selected the option Acceptance Required = Signature (available through the Terms button on the PO).
• In this case, the PO goes to the Supplier for signature after the final approver (Level 4).
• Once the Supplier approves, it is routed back to the Buyer.
• We need clarification on whether this is the intended behavior and how to properly configure it to meet our requirement.