Create PowerShell PSObject in C# cmdlet

You can mirror the behavior of Add-Member simply by calling Add() on the Members property of your PSObject (I would change the property names to CamelCase for ease of accessibility in PowerShell):

if (requestModel != null && requestModel.Response != null){    PSObject responseObject = new PSObject();    responseObject.Members.Add(new PSNoteProperty("SiteID", requestModel.Response.SiteID));    responseObject.Members.Add(new PSNoteProperty("Identity", requestModel.Response.SiteName));    // and so on etc...     responseObject.Members.Add(new PSNoteProperty("Latitude", requestModel.Response.latitude));    this.WriteObject(responseObject);}

Without knowing all the details I can't say this is the best plan, but here is what I would do. You could define a class and then return it. So you would create a new class such as below:

public class RequestResponse {    public int SiteID { get; set;}    public string Identity { get; set; }    other fields...}

Next, in the code you posted, you would create the object and then fill the properties of the class.

var response = new RequestResponse();if (requestModel != null && requestModel.Response != null){    response.SiteID = requestModel.Response.SiteID;    response.Identity  = requestModel.Response.Identity ;    fill in other fields...    this.WriteResponse(requestModel, response);}

I hope this gets you started in the right direction.

Wade