cProject write authorization

We have a set-up where we create item linked with cproject, cproject gets the role inherited from cproject template while item inherits from portfolio. Although we have a authorization synch config done. To modify the project structure and status or dated, we just want to give write authorization to user. But the issue is that cproject gets the role (with write autho)  from cproject template , user can only display the project can't change anything on it. How can we achieve that user could change structure, the dates and status on tasks,  just giving write autho on project.