get mdi child node

Hi I am trying to find all mdi menu items and menu items child and there child. in mdi there is three level for menu.
now problem is I am able to find child upto second level, please help me to find the third level child. for example: Master->Station->domestic , I am able to search till station not domestic below is the code.


 public void SecurityCheck(MDIColts ObjMdi)
        {
            Int32 Count;

            if (Global.GetInstance.LoggedInUserType != "SA")
            {
                foreach (ToolStripMenuItem tsmi in menuStrip.Items)
                {
                    if (colMenuItem.Contains(tsmi.Name) == true)
                    {
                        tsmi.Visible = true;
                    }
                    else
                    {
                        tsmi.Visible = false;
                    }
                   for (Count = 0; Count < tsmi.DropDownItems.Count; Count++)
                    {
                        if (colMenuItem.Contains(tsmi.DropDownItems[Count].Name) == true)
                        {
                            tsmi.DropDownItems[Count].Visible = true;
                        }
                        else
                        {
                            tsmi.DropDownItems[Count].Visible = false;
                        }
                      
                }
            }
            else
            {
                foreach (ToolStripMenuItem tsmi in menuStrip.Items)
                {
                    tsmi.Visible = true;
                    for (Count = 0; Count < tsmi.DropDownItems.Count; Count++)
                    {
                        tsmi.DropDownItems[Count].Visible = true;
                    }
                }
            }
        }