Extending the FHIR Resource Model and adding those extensions to SDA3 so that I can create FHIR->SDA3 and SDA3 - FHIR DTL's

I need to add some extensions to the HS.FHIR.vSTU3,Model.Resource.Patient class and then use those extensions to convert incoming FHIR JSON to the FHIR Patient Resource and Likewise add functionality to create A FHIR Patient (target class) from my patient database into the FHIR Patient  Resource Object (target class)

many months ago I found a tutorial that explained all of this but can no longer find that tutorial.

Yours

Nigel Salm