Hi,
You will have to edit the file "administrators/components/com_hikashop/classes/filter.php" and in the function "getManufacturers()" replace the line:
$query='SELECT a.* FROM '.hikashop_table('category').' AS a '.$left.' WHERE a.category_type="manufacturer" AND a.category_parent_id!=\'1\' '.$optionElement.' AND a.category_published=1 ORDER BY a.category_ordering ASC';
By:
$query='SELECT a.* FROM '.hikashop_table('category').' AS a '.$left.' WHERE a.category_type="manufacturer" AND a.category_parent_id!=\'1\' '.$optionElement.' AND a.category_published=1 ORDER BY a.category_name ASC';
We will see if we can't add an option for that.