I have searched and not found an answer for this (nor did Google help). We are on Project Server 2007. I am running a large program with multiple project managers handling different parts of the program. I would like to allow one of my project managers to get into the master plan to update it. I cannot for the life of me figure out how to allow this in Project Server for this particular project.
This question is quite old. I'm adding an answer so it could help someone looking for the same solution.
In Project Server 2007 you can do the following:
Create a security category and include that project in the category.
Create a security group and apply the security template corresponding to the "Portfolio Managers" group (that is, permissions should be the same). However, this group should belong only to the "My Projects" and "My Tasks" categories. Also, add the new category you created. Finally, include the project managers to this group.
This way, those project managers will have Portfolio Managers privileges but only over this particular project.
If it doesn't work, you can try adding the project managers to the new category and see if it works.
On later Project Server versions, this method only works if security is configured as "Project Server Security". In Sharepoint security it's easier: just search for the security groups created for that project; one of these groups is related to Project Managers, you only have to add the users to that group.
Hope this helps.