SS3.1

Back in the DOM days, I had this working, but haven't found a solution in SS3.

How can I hide some fields for MenuPage but show it on MenuPageFamilyMeals without creating two DataObjects?

class MenuItem extends DataObject {

    private static $db = array(
	  'MenuItemName' => 'HTMLVarchar(80)',
	  'MenuItemDescription' => 'HTMLText',
	  'FamilyMeal' => 'Enum("Family_Meal,Additional_Family_Meal")'
     );

     private static $has_one = array(
	'MenuPageFamilyMeals' => 'MenuPageFamilyMeals',
	'MenuPage' => 'MenuPage'
     );

    function getCMSFields() {
      $fields = parent::getCMSFields();
   
      ...

      return $fields;
     }

}

Thanks