public static frmSubscribePersonImport GetInstance()
 {
     if (frmSubscribersImport == null)
     {
         frmSubscribersImport = new frmSubscribePersonImport();
     }
     return(frmSubscribersImport);
 }
        private void button1_Click(object sender, EventArgs e)
        {
            frmSubscribePersonImport fm = frmSubscribePersonImport.GetInstance();

            fm.ShowDialog();
        }