서브 메뉴에 추가할수 있는 방법이 있을까요??

<nav class="gnb">

            <ul>

                <?php

                $menu_datas = get_menu_db(0, true);

                $cur_url = $_SERVER['REQUEST_URI'];          

                $gnb_zindex = 999; // gnb_1dli z-index 값 설정용

                $i = 0;         

                foreach( $menu_datas as $row ){

                ?>

                

                <li class="depth1 <?php echo ($row['me_link']==$cur_url)?'on':''; ?>">

                    <a href="<?php echo $row['me_link']; ?>" target="_<?php echo $row['me_target']; ?>" class="gnb_al_a"><?php echo $row['me_name'] ?></a>

                    <i class="fa fa-chevron-down mobile_only" aria-hidden="true"></i>

                    <?php

                    $k = 0;

                    foreach( (array) $row['sub'] as $row2 ){

                        if($k == 0)

                            echo '<ul>'.PHP_EOL;

                    ?>

                        <li class="depth2"><a href="<?php echo $row2['me_link']; ?>" target="_<?php echo $row2['me_target']; ?>"><?php echo $row2['me_name'] ?></a></li>

                    <?php

                    $k++;

                    }   //end foreach $row2

 

                    if($k > 0)

                        echo '</ul>'.PHP_EOL;

                    ?>

                </li>   

                <?php } ?>      

            </ul>

            <ul class="login_info">

                <?php if ($is_member) {  ?>

                <!-- <li><a href="<?php echo G5_BBS_URL ?>/member_confirm.php?url=/register_form.php">My page</a></li> -->

                <li class="depth3"><a href="<?php echo G5_BBS_URL ?>/logout.php">로그아웃</a></li>              

                <?php } else {  ?>              

                <li class="depth3"><a href="<?php echo G5_BBS_URL ?>/login.php">로그인</a></li>

                <li class="depth3"><a href="<?php echo G5_BBS_URL ?>/register.php">회원가입</a></li>

                <?php }  ?>

                <?php if ($is_admin) {  ?>

                <li class="depth3 admin"><a href="<?php echo correct_goto_url(G5_ADMIN_URL); ?>" target="_blank">관리자</a></li>

                <?php }  ?>

            </ul>

        </nav>