I'm trying to set an appointment's default value for TimeMarkerID for new appointments. When I add code in either the SqlAppointment's constructor or ViewModels' OnAppointmentsCollectionChanged and then hit the save button on the appointment it appears to try and save the appointment twice. The second appointment has all values blank except for the timemarker default value. I then get an exception of 'The conversion of a datetime2 data type to a datetime data type resulted in an out-of-range value.' because the start/end times are 1/1/0001.
Note: Neither appointment actually saves to SQL.
Is there a way to set the default value of TimeMarkerID?