Purchase requisition edit by approver

Hi, 

I am using AX 2012 - with regards to purchase requisition workflows, a requirement is for the approver to be able to edit the vendor on the purchase requisition lines prior to approving. However, it seems that the approver cannot edit the purchase requisition lines and must therefore turn to the "request a change" option which routes the purchase requisition line back to the submitter to edit.

Is there any configuration related to allowing the approver to edit the purchase requisition lines directly please?

Thanks in advance,

Alexia