FB, limiting crosslink options table

Hi, I'm new to DO + FB and I have a question if is poslible in some simple way to do whereAdd() on the options table? from /DB/DataObject/FormBuilder.php -----------------------------------------

1     *
2     * @return array strings representing all of the records in $table.
3     * @access protected
4     */
5    function _getSelectOptions($table, $displayFields = false, $selectAddEmpty = false, $field = false, $valueField = false) {
6        $opts =& DB_DataObject::factory($table);
7        $opts->whereAdd("Something = 'N'");
8                        ^^^^^^^^^^^^^^^ # query on the options table
9        		
10        if (is_a($opts, 'db_dataobject')) {
11           if ($this->isCallableAndExists($this->prepareLinkedDataObjectCallback)) {
12                call_user_func_array($this->prepareLinkedDataObjectCallback, array(&$opts, $field));
13            }
14            if ($valueField === false) {
15                $valueField = $this->_getPrimaryKey($opts);
16            }

I don't want do display all the resolts from the table I have try with adding $linkedDataObject->whereAdd("Something = 'N'") in prepareLinkedDataObject(), but this add the "Something = 'N'" to both tables (linking and options? table). thanks, d30