public partial class Main : oRRoSoft.Windows.Forms.Form
{
    public Main() : base()
    {
        InitializeComponent();
    }
 
    public Main(string Text) : this()
    {
        m_Text = Text;
    }
}
 
 
public partial class Formular() : Main
{
    public Formular() : base()
    {
        InitializeComponent();
    }
}
 
// aufruf
Formular frm = new Formular(????);