Highlight the links without using dropdown

SOLUTION

I found it by using the <?php wp_list_pages( $args ); ?> with customizing the args to display only selected children by id.

$args = array (
    'title_li'  => '',
    'child_of'  => $post->ID,
    'include'  => 47
    )

<h4> <?php wp_list_pages( $args ); ?> </h4>

and setting the css to target the current and its parent using wordpress default css.

.current-menu-item, .current-page-ancestor {
    /* css */
    }