Authorization for PM Order User Statuses

Hi PM Experts,

I have three user statuses in PM Order (* Status A, B & C*) and they have different Authorization Keys ( Auth.Key A, B & C respectively). The orders are created in Status A (initial status).

I have User B & C, where User B should be able to change the user status of the order from Status A to B . But should not be allowed to change to Status C. User C should be able to change the order from user Status B to C. All the above I managed to control through authorization.

But the tyricky part is User B shouldn't be able to change the orders back from Status C to B. How do you control this using Authorization object B_USERSTAT.

In Authorization object B_USERSTAT for each Authorization Key there are two statuses Create and Delete meaning to change to a user status and change from a user status respectively. In the above case I have to give Auth.Key B Create Access to User B but once its given, he gets the access to change Status C to B as well. However User B doesn't have Delete Access for Status C. But he could still do the above.

Can anyone suggest a method to handle the situation, please ?

Cheers

Deepal