Hi Juergen, I had a similar requirement we I wanted to give my PMO access rights to changes any field. I opted for a basic workflow rule that gave anyone in my Manager Group access. When we create a project, the rule runs and adds all PMO members to the Manager group. This works very well for us. The downside is that if you applied the same approach, then every field could be edited by anyone
Alternatively, you could review the options in Profile Permissions to see if you can restrict to the Work Plan only for example