The RecurrenceParentID is the ID of the master appointment which is stored in the database. For more information please review this topic: Working with Recurring Appointments
The CheckBox filtering could be achieved by slightly modifying the code in this live demo of ours - Defining Resources
I have attached the modified version of the page to this post. Please download it and examine it.
It would be best if you first back up the old page (in the installation directory of RadControls for ASP.NET AJAX) and then replace it with the attached to observe the approach in action.
the Telerik team