WA permission in workflow

System

Hi,

I have a specific requirement in a workflow as underlined below -

I create a WA during the course of the workflow (through an external task) and make one user (writer) owner of it. The WA has 770 permission meaning "others" won't be able to see the WA. Now that owner will create or modify a file and send that for further editing to another user. That 2nd user must have write access to the workarea as he needs to work on the file. I can add that 2nd user to the Group that shares the WA. After editing the file needs to be send to reviewers for review. Now those reviewers should only have read only access to the WA. So I can not add them to the same group as editor. Also reviewers can not be "others" as they need read access to the WA.

Appreciate if any body could throw some light on how this can be acheived.

Thanks

-PB