How do you create a custom edit.php / edit pages page

Question

I need to create 3 custom edit.php pages which only display pages with a certain parent and the Post New button links to a new page with the corresponding parent.

The closest answer I can is do not edit core files and just remove meta boxes etc. How can I customize "Pages" admin (edit.php) and "Edit Page" admin (post.php) for bulk edit of custom content type?

But I cannot do this. Any suggestions how I can duplicate the edit.php page?

So far I duplicated the code into my template but it displays no pages:

Answer 1

A menu solution is possible, and I'll tackle it at the end, but another one it to add the custom links with the hook views_edit-$post_type.

My Account and Checkout are two parent pages. Their links will use hardcoded page IDs: edit.php?post_type=page&checkout=1669 and we will catch the $_GET['checkout'] parameter to call a pre_get_posts hook.

# Called only in /wp-admin/edit.php* pages
add_action( 'load-edit.php', function()
{
    # Not our post_type, bail out
    if ( get_current_screen()->id != 'edit-page' )
        return;

    # Transient cache for pages IDs and Count
    # used in both hooks bellow
    do_cache_wpse_77721();

    # Check if our Query Var is defined and activate pre_get_posts   
    if( isset( $_GET['account'] ) || isset( $_GET['checkout'] ) )
        add_action( 'pre_get_posts', 'pre_posts_wpse_77721' );

    add_filter( 'views_edit-page', 'custom_links_wpse_77721' );
});

/**
 * Only display comments of specific post_id
 */ 
function pre_posts_wpse_77721( $query )
{
    # Just to play safe, but I think the hook is quite specificaly called
    if( !is_admin() )
        return $query;

    global $pagenow;

    # If there's no cache, bail out
    $cache = get_transient( 'custom_page_links' );
    if( !$cache )
        return $query;

    # Define the IDs we want to query
    if( isset( $_GET['account'] ) )
        $ids = $cache['account']['ids'];
    else
        $ids = $cache['checkout']['ids'];

    # Here, too, just playing safe
    if( 'edit.php' == $pagenow && ( get_query_var('post_type') && 'page' == get_query_var('post_type') ) )
        $query->set( 'post__in', $ids );

    return $query;
}

/**
 * Add link to specific post comments with counter
 */
function custom_links_wpse_77721( $status_links )
{
    $cache = get_transient( 'custom_page_links' );
    $count_checkout = sprintf(
        '<span class="count">(%s)</span>',
        $cache['checkout']['count']
    );
    $count_account = sprintf(
        '<span class="count">(%s)</span>',
        $cache['account']['count']
    );

    $link_account = 'edit.php?post_type=page&account=1670';
    $link_checkout = 'edit.php?post_type=page&checkout=1669';
    $link_all = '<a href="edit.php?post_type=page">All</a>';
    $separator = 'CUSTOM LINKS &#x27BD;';

    if( isset( $_GET['checkout'] ) ) 
    {
        $status_links['all'] = $link_all;
        $status_links['my_sep'] = $separator;
        $status_links['account'] = "<a href='$link_account'>My Account $count_account</a>";
        $status_links['checkout'] = "<a href='$link_checkout' class='current'>Checkout $count_checkout</a>";
    }                             
    elseif( isset( $_GET['account'] ) ) 
    {                             
        $status_links['all'] = $link_all;
        $status_links['my_sep'] = $separator;
        $status_links['account'] = "<a href='$link_account' class='current'>My Account $count_account</a>";
        $status_links['checkout'] = "<a href='$link_checkout'>Checkout $count_checkout</a>";
    }                             
    else                          
    {                             
        $status_links['my_sep'] = $separator;
        $status_links['account'] = "<a href='$link_account'>My Account $count_account</a>";
        $status_links['checkout'] = "<a href='$link_checkout'>Checkout $count_checkout</a>";
    }

    return $status_links;
}

/**
 * Makes the query once every hour
 * holds the Parent and Children ID, plus the Children total pages count
 */
function do_cache_wpse_77721()
{
    if( !get_transient( 'custom_page_links' ) )
    {
        # Page 1
        $checkout_posts = get_children( 'post_parent=1669&post_type=page' );
        // To include the parent ID in the query
        $c_ids = array( '1669' ); 
        // Grab the children IDs
        foreach( $checkout_posts as $check )
            $c_ids[] = $check->ID;
        $checkout = array( 
            'ids' => $c_ids,
            'count' => count( $checkout_posts )
        );

        # Page 2
        $account_posts = get_children( 'post_parent=1670&post_type=page' );
        $a_ids = array( '1670' );
        foreach( $account_posts as $acc )
            $a_ids[] = $acc->ID;
        $account = array( 
            'ids' => $a_ids,
            'count' => count( $account_posts )
        );

        # Set transient
        $transient = array(
            'checkout' => $checkout,
            'account' => $account
        );
        set_transient( 'custom_page_links', $transient, 60*60 );
    }
}

And here's how to add a submenu to Pages, that links directly to one of the parent pages. We have to use jQuery to adjust the active/inactive states for the menu and submenu.

add_action('admin_menu', function() 
{
    add_submenu_page(
        'edit.php?post_type=page', 
        'Checkout', 
        'Checkout', 
        'edit_pages', 
        'custom_parent_page', 
        function()
        { 
            wp_redirect(admin_url('edit.php?post_type=page&checkout=1669')); 
            exit; 
        }
    );
});