AX 2012 PR workflow


I have an issue in one of the implementation in AX 2012 Feature pack

The requirement is

Once the Purchase requisition is prepared and submitted into the workflow. The Buyer will get get the Quotations (RFQ) from Vendor and will compare the RFQ and seleect the best vendor. Once this is done the PR lines automatically gets populated with the correct values and then the workflow moves for Managerial approval.

Here the challenge starts.

If the workflow reached a Manager for his approval, currently he has the edit privilege on the Workflow and he may modify the price and approve it; The next manager (who is ignorant of the changes) simply approves it and it goes on…

(of course we can set alerts for tracking purpose, also we can do the comparison of PR etc…)

But my question here is, Is there a way where by we restrict all the Managers from editing the PR, but they will be able to view the contents, and either approve it or reject it.

Assume in the olden days, we we prepare a PO; put the details of items and price and value. Managers can see the details and if they agrees, they will OK it else reject it, but no changes are allowed on the document. This is exactly what we are looking for

Any idea?