There are two ways to add appointments to a shared calendar:

1) click on the calendar and set the subject, location, time and description of the appointment

2) click on your personal calendar, set the subject, location, time and description of the appointment and send it to the shared calendar

The first option allows for unclear appointment titles, whereas the second option automatically states the name of the person who made the appointment. For this reason, I want option 2 to be the only possible option and I want to block the ability to make an appointment on the shared calendar via option 1.

tl;dr: allow option 2, block option 1