private function addElement($elem, $to_add)
    {
        //debug_var_dump("to_add->$elem", $to_add->$elem);
        if (isset($to_add->$elem) && !empty($to_add->$elem) && $to_add->$elem != ' ') {//&& !empty(str_replace(' ', '', $to_add->$elem)) ){
            $elem_to_add = str_replace('&', '-and-', $to_add->$elem); //replace amperstamps for -and-
            if (!in_array($elem_to_add, $this->$elem)) {
                array_push($this->$elem, $elem_to_add);
                //debug_var_dump("this->$elem", $this->$elem);
            }
        }
    }