wp_insert_post() 返回新帖子的帖子ID。您可以使用该ID设置父帖子。

实例

$about_id = wp_insert_post(
    array (
        \'post_title\'   => \'About\',
        \'post_status\'  => \'publish\',
        \'post_type\'    => \'page\',
    )
);
wp_insert_post(
    array (
        \'post_title\'   => \'Information\',
        \'post_status\'  => \'publish\',
        \'post_type\'    => \'page\',
        \'post_parent\'  => $about_id,
    )
);

在您的情况下，我将重新构造页面数据并构建嵌套数组：

$default_pages = array(
    \'Contact\'     => array(
        "content" => "This is your \'Contact\' page. Enter in your content here."
    ),
    \'About\'       => array(
        "content" => "This is your \'About\' page. Enter in your content here.",
        "children" => array(
            \'Information\' => array(
                "content" => "This is your \'Information\' page. Enter in your content here."
            )
        ),
    ),
    \'Home\'        => array(
        "content" => "This is your \'Home\' page. Enter in your content here."
    ),
);

然后，我将页面插入移动到一个单独的函数，以允许递归：

function insert_page( $title, Array $properties, $post_parent = 0 )
{
    $data = array(
        \'post_title\'   => $title,
        \'post_content\' => $properties[ "content" ],
        \'post_status\'  => \'publish\',
        \'post_type\'    => \'page\',
        \'post_parent\'  => $post_parent,
    );

    $id = wp_insert_post( add_magic_quotes( $data ) );

    if ( ! empty ( $properties[ "children" ] ) )
    {
        foreach ( $properties[ "children" ] as $child_title => $child_properties )
            insert_page( $child_title, $child_properties, $id );
    }
}

因此，您的完整代码应该如下所示：

function default_pages( $blog_id )
{
    $default_pages = array(
        \'Contact\'     => array(
            "content" => "This is your \'Contact\' page. Enter in your content here."
        ),
        \'About\'       => array(
            "content" => "This is your \'About\' page. Enter in your content here.",
            "children" => array(
                \'Information\' => array(
                    "content" => "This is your \'Information\' page. Enter in your content here."
                )
            ),
        ),
        \'Home\'        => array(
            "content" => "This is your \'Home\' page. Enter in your content here."
        ),
    );

    switch_to_blog( $blog_id );

    if ( $current_pages = get_pages() )
        $default_pages = array_diff( $default_pages, wp_list_pluck( $current_pages, \'post_title\' ) );

    foreach ( $default_pages as $page_title => $properties )
        insert_page( $page_title, $properties );

    restore_current_blog();
}

function insert_page( $title, Array $properties, $post_parent = 0 )
{
    $data = array(
        \'post_title\'   => $title,
        \'post_content\' => $properties[ "content" ],
        \'post_status\'  => \'publish\',
        \'post_type\'    => \'page\',
        \'post_parent\'  => $post_parent,
    );

    $id = wp_insert_post( add_magic_quotes( $data ) );

    if ( ! empty ( $properties[ "children" ] ) )
    {
        foreach ( $properties[ "children" ] as $child_title => $child_properties )
            insert_page( $child_title, $child_properties, $id );
    }
}