Customizing CalDAV for Selective Calendar Event Synchronization

Question

Hi StackOverflow Community,

I'm working on implementing a calendar solution using CalDAV, specifically with Apple's implementation. Our requirement is somewhat unique:

1. Customers Book Appointments: We need a system where customers can book appointments.
2. Synchronization with Service Partners: These appointments should then synchronize with the calendars of service partners.
3. Privacy for Service Partners: Our service partners have other appointments in their calendars that they don't want to share with us. So, we need a way to sync only the appointments booked by customers to our system.
4. Partial Visibility in Sync: For the service partners' self-added appointments, we want to see only a "blocked" or "busy" status in our calendar without any details of the appointment.

The challenge is setting up the CalDAV server to allow this selective synchronization and partial visibility. I am looking for guidance or suggestions on how to achieve this. Is this possible with standard CalDAV features, or would it require a customized solution? If customization is needed, what approach and tools would you recommend?

Any insights or pointers would be greatly appreciated.

Thank you!