The requirement from the customer is to be able to add Posts to an Appointment or to a Phone Call (or to any other activity), because in Posts they can tag other users and contacts.
I understand it's not possible to add the Timeline control in forms of Activity entities (like Appointment and Phone Call), but in these entities you have a special "Notes" control that allows users to add Notes.
I didn't find a way to enable Posts in the "Notes" control of an activity form. I've tried in the Appointment entity and in a custom Activity entity.
Is there anyway I could achieve this?
The customer is open to solutions that involve development, I just didn't want to build all the tagging functionality in a PCF.