WordPress sidebar: query specific pages based on current page

I have three pages in my WordPress site: About, Voices & History. These are all using the same template. Each of these are parent pages to several additional respective sub-pages (i.e. About is parent to five About sub-pages). All of the parent pages use the same sidebar.php file.

Is it possible for the sidebar to display only the parent's respective sub-pages?

For example, if the user is on the About page, the sidebar would query and only display About sub-pages. If they're on the Voices page, the sidebar changes to display only Voices sub-page开发者_如何学JAVAs.

I've been unsuccessful in my attempts. Any code to accomplish this is greatly appreciated.

What you could do is, in you loop do this:

<?php
//calling loop stuff here
// bla bla
// stores post that will have related posts
global $related;
$related = $post->ID;
// end loop
?>

Then, in your sidebar you do this:

<?php
//common sidebar stuff here
//bla bla
//check if has related posts
global $related;
if (!empty($related)) {
//call related posts here
}
?>