[NumLock]

1. наследовать С2 от TPersistent
2. переопределить метод Assign в С2
3. использовать в дальнейшем Assign

Код:

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs;

type
  TC2 = class(TPersistent)
  public
    SProp: String;
    IProp: Integer;
    procedure Assign(Source: TPersistent); override;
  end;

  TForm1 = class(TForm)
    procedure FormCreate(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

{ TC2 }

procedure TC2.Assign(Source: TPersistent);
begin
  SProp:=TC2(Source).SProp;
  IProp:=TC2(Source).IProp;
end;

procedure TForm1.FormCreate(Sender: TObject);
var
  c21: TC2;
  c22: TC2;
begin
  c21:=TC2.Create;
  c22:=TC2.Create;
  c21.SProp:='hello world';
  c21.IProp:=255;
  c22.Assign(c21);
  c21.Free;
  ShowMessage(c22.SProp+' '+IntToStr(c22.IProp));
  c22.Free;
end;

end.