Please, excuse us for the delayed response.
The provider is not really supposed to care if the appointment is recurring or not. At least not in the majority of the scenarios. It's only responsible for processing the appointment instance that is being passed. It's a responsibility of the WebServiceAppointmentController to issue the correct operations for the correct appointments when processing recurring appointments.
That said, you can still distinguish between updating the series or a single appointment by using the ProviderContext
property, but this shouldn't be necessary in your scenario.
I hope this helps.
All the best,
the Telerik team