Accessing and editing categories by another user in timesheet

Hi,
I’ve just set up egroupware server in our small company and have an issue.
The main component used here is timesheet.
I want to be able to grant permissions to users to create categories, so that other other clients also see this categories. Is it achievable without granting in ACL right to see everything by the group, because then the whole group will see other users timesheets and i want them only to see and use categories crated by other users.
Also I want to set a group of administrators that have right to access and edit everything, including categories crated by other users. But againt categories are avaible to be edited only by users who created them (not even the administrator of whole egroupware).
How can I achieve that ?