PO Creation and Change Authorisation

Hi

The scenario is,

User 1 - Can create PO , change Po and display PO

User 2 - Can create PO and display PO only

Why becoz PO ammenment shld be done by User 1 only like Price and qty changes, So we hv removed the change Po autho to User 2.

It create a pblm of User cant do any change in Po by me22n. Its not actually we want.

So we are thinking to control User 2 autho by they can create Po, change PO and release PO.

After final release User 2 shold be restriced to change the PO but user 1 can change the PO

How to control this?

Vijay