Embed application to windows form quietly

Question

I have an application that I am embedding into a form. That works fine, however, I would like to try to do it quietly (not visible).
I have tried using the property WindowStyle = ProcessWindowStyle.Minimized;, however it still showed up, not being Minimized.

this.BeginInvoke((Action)async delegate ()
            {
                Process p = Process.Start(svPath);
                p.WaitForInputIdle();
                await Task.Delay(5000);
                SetParent(p.MainWindowHandle, panel2.Handle);
                SetWindowLong(p.MainWindowHandle, GWL_STYLE, WS_VISIBLE);
                MoveWindow(p.MainWindowHandle, 0, 0, panel2.Width, panel2.Height, true);
            });