Is there a way to set the CreatedBy for a new discussion or comment

We are looking for a way to create a new comment from a specific user that is not the same as the user in which the API is called from. It would be fine if we could change the createdby after the discussion is created too, I have tried that too with no luck. Here is the code we are trying:

 Comment c = new Comment();

          c.Text = message;

          c.CreatedBy = new User();

          c.CreatedBy.Email = "NonAPI@email.com";

          Discussion d = new Discussion();

          d.Comment = c;

          Discussion newD = smartsheet.SheetResources.RowResources.DiscussionResources.CreateDiscussion(123654, 654321, d);