Planned Interventions -access rights

Good day everyone, 
I am currently looking into the planned interventions. My goal is to have my projeqtor users who are also 'projects members' able to select an acctivity and plan their interventions, this  regardless of their 'project activity' role or 'project' rights.
Until now I tested and a project member default role with manager or analyst rights for project and/or activity cannot select an activity and plan its intervention.
Can you advise what's up regarding such an issue ? I don't find anything about the required rights in the documentation or forum.
thank you very much in advance,