Дозапись из Memo в файл через SaveDialog

procedure TForm1.N2Click(Sender: TObject);
begin
 if OpenDialog1.Execute then
      Memo1.Lines.LoadFromFile(OpenDialog1.FileName);
 end;
 
 
procedure TForm1.N3Click(Sender: TObject);
begin
  If SaveDialog1.Execute Then
Begin
Memo1.Lines.SaveToFile(SaveDialog1.FileName);
Memo1.Lines.LoadFromFile (SaveDialog1.FileName);
End;

var
FFile:TsrtingList;
i:integer;
begin
FFile:=TstringList.Create;
 if OpenDialog1.Execute then
      FFile.LoadFromFile(OpenDialog1.FileName);
for i:=0 to ffile.count-1 do 
  memo1.lines.add(ffile.strings[i]);
freeandnill(ffile);

procedure TForm100500.N100500Click(Sender: TObject);
var
  FFile:TSrtingList;
begin
  if not SaveDialog.Execute()
    then Exit;
    
  FFile:= TStringList.Create();
  try
    try
      FFile.LoadFromFile(SaveDialog.FileName);
      FFile.AddStrings(Memo.Lines);
      FFile.SaveToFile(SaveDialog.FileName);
      Memo.Clear();
    except on E: Exception do
             begin
               MessageBox(0, PChar(E.Message),
                          PChar('fuckit x32!'),
                          mb_Ok + mb_IconError);
    end;     end;
  finally
    FFile.Free();
  end;
end;

procedure TForm1.Button3Click(Sender: TObject);
 
var
  FFile:TstringList;
begin
  if not SaveDialog1.Execute()
    then Exit;
 
  FFile:= TStringList.Create();
  try
    try
      FFile.LoadFromFile(SaveDialog1.FileName);
      FFile.AddStrings(Memo1.Lines);
      FFile.SaveToFile(SaveDialog1.FileName);
      Memo1.Clear();
    except on E: Exception do
             begin
               MessageBox(0, PChar(E.Message),
                          PChar('fuckit x32!'),
                          mb_Ok + mb_IconError);
    end;     end;
  finally
    FFile.Free();
  end;
end;

procedure AddRec(Rec, FileName: String);
var
F: TextFile;
begin
AssignFile(F,FileName);
Append(F);
WriteLn(Rec);
CloseFile(F);
end;

Write(F, Rec);

procedure AddRec(const Rec, FileName: String);
var
  F: TFileStream;
begin
  if Rec = ''
    then Exit;
    
  F:= TFileStream.Create(FileName, fmOpenReadWrite);
  try
    F.Position:= F.Size;
    F.WriteBuffer(Rec[1], Length(Rec));
  finally
    F.Free();
  end;
end;