Form 1
==================

var
  Form1: TForm1;

implementation

uses Unit2;

{$R *.DFM}

procedure TForm1.Grid1DblClick(Sender: TObject);
begin
  if not Assigned(Form2)
  then Form2 := TForm2.Create(Application);
  with Form2 do
  begin
    Form2.q1.Open;
    Form2.q1.BeginCachedUpdates;
    // Form1.q1.Refresh;    // Updates fail without this line
    Form2.q1.Edit;
    Show;
  end;
end;

Form 2
==================

var
  Form2: TForm2;

implementation

uses Unit1;

{$R *.DFM}

procedure TForm2.FormClose(Sender: TObject; var Action: TCloseAction);
begin
  Action := caFree;
  Form2 := nil;
end;

procedure TForm2.RzButton1Click(Sender: TObject);
begin
  q1.Post;
  q1.ApplyCachedUpdates;
  Form2.Close;
  Form1.q1.Refresh;
end;