Roles required for editing PO during approval
SummaryApprover needs to edit PO for auto-submitted PR-backed POs
The business case is that the finance approvers for a PO need to change the incorrectly put expenditure type on the PO distribution lines. The PO arrives to them only at the time of approval. Many POs are also auto generated, which means that they do not have any buyer's intervention.
Now, if the approver rejects the PO, it shall be the Buyer's onus to make changes on it. Since buyers do not take responsibility of automatically generated POs from PRs (those generated with reference to a BPA or already negotiated with supplier), rejecting a PO to buyer for changes would create a conflict. Furthermore, the signed off business process at the customer requires the Finance PO approvers to make appropriate changes on the PO when PO is automatically created from a backing PR.