<!--{if $arrTree[cnt].parent_category_id == 1 || $arrTree[cnt].category_id == 1}-->

そこで、下記のコードのかわりに、
<!--{if $category==1}-->
↓
下記にしたのですが、やはり表示されず…。
<!--{if $arrTree[cnt].level <=99 && $arrTree[cnt].parent_category_id == 1 && $arrTree[cnt].category_id == 1}-->
↓
下記のように、すると子だけは表示されるようになりましたが、
親は表示されない。。
<!--{if $arrTree[cnt].level <=99 && $arrTree[cnt].parent_category_id == 1}-->

            foreach ($arrRet as &$arrCategory) {
                if (in_array($arrCategory['category_id'], $arrDispID)) {
                    $arrCategory['display'] = 1;
                }
            }

            foreach ($arrRet as &$arrCategory) {
                    $arrCategory['display'] = 1;
            }

function lfGetCatTree($arrParentCategoryId, $count_check = false) {
        $objQuery =& SC_Query_Ex::getSingletonInstance();
        $objDb = new SC_Helper_DB_Ex();
        $col = '*';
        $from = 'dtb_category left join dtb_category_total_count ON dtb_category.category_id = dtb_category_total_count.category_id';
        // 登録商品数のチェック
        if ($count_check) {
        //    $where = 'del_flg = 0 AND product_count > 0';
			$where = "del_flg = 0";
        } else {
            $where = 'del_flg = 0';
        }
        $objQuery->setOption('ORDER BY rank DESC');
        $arrRet = $objQuery->select($col, $from, $where);
        foreach ($arrParentCategoryId as $category_id) {
            $arrParentID = $objDb->sfGetParents(
                'dtb_category',
                'parent_category_id',
                'category_id',
                $category_id
            );
            $arrBrothersID = SC_Utils_Ex::sfGetBrothersArray(
                $arrRet,
                'parent_category_id',
                'category_id',
                $arrParentID
            );
            $arrChildrenID = SC_Utils_Ex::sfGetUnderChildrenArray(
                $arrRet,
                'parent_category_id',
                'category_id',
                $category_id
            );
            $this->root_parent_id[] = $arrParentID[0];
            $arrDispID = array_merge($arrBrothersID, $arrChildrenID);
            foreach ($arrRet as &$arrCategory) {
                if (in_array($arrCategory['category_id'], $arrDispID)) {
                    $arrCategory['display'] = 1;
                }
            }
        }
        return $arrRet;
    }

            foreach ($arrRet as $key => $array) {
                foreach ($arrDispID as $val) {
                    if ($array['category_id'] == $val) {
                        $arrRet[$key]['display'] = 1;
                        break;
                    }
                }
            }
を
            foreach ($arrRet as $key => $array) {
                foreach ($arrDispID as $val) {
                    $arrRet[$key]['display'] = 1;
                }
            }

<!--{assign var=category value=`$arrTree[cnt].category_id`}-->
<!--{if $category==1}-->

<a href="<!--{$smarty.const.ROOT_URLPATH}-->products/list.php?category_id=<!--{$arrTree[cnt].category_id}-->" class="level<!--{$level}--><!--{if in_array($arrTree[cnt].category_id, $tpl_category_id)}--> onmark<!--{/if}-->"><!--{$arrTree[cnt].category_name|h}--></a>

<!--{/if}-->

$arrTree[cnt].category_id