-$form->addInput(array('type'=>'combobox','onchange'=>'handleCheckboxes();','name'=>'group_by','data'=>$group_by_options));
+$group_by_options_size = sizeof($group_by_options);
+$form->addInput(array('type'=>'combobox','onchange'=>'handleCheckboxes();','name'=>'group_by1','data'=>$group_by_options));
+if ($group_by_options_size > 2) $form->addInput(array('type'=>'combobox','onchange'=>'handleCheckboxes();','name'=>'group_by2','data'=>$group_by_options));
+if ($group_by_options_size > 3) $form->addInput(array('type'=>'combobox','onchange'=>'handleCheckboxes();','name'=>'group_by3','data'=>$group_by_options));