Only the lecturers (or designers) of the course have the acces to the tentamenlade. They form an author group. They can have the write or read rights. Who may see a tentamenlade and with which rights is set by the admin in concert with the lecturers.
In the case that teachers from different institutions collaborate in tentamenlade different scenarios are possible. The usual choice up to now was that they can see and use the material of each other (read rights). If they wish to change an item of another party they can copy it to a new question for which they get their write rights. The other party gets automatically the read rights for it.