This plugin allows you to filter pages by parent in the admin dashboard.

douglaskarr

List Child Pages Shortcode

A simple plugin to add list of child pages within the content of a parent page.

Julio Potier

Multiple Passwords for Protected Pages

Add more than 1 password to your protected pages, also administrators and page's authors can view the protected pages without password.

EngageWeb

nickarkell

Dynaparent – Dynamic Parent Filter

Dynaparent (Dynamic Parent) makes it much easier to choose a parent page on websites that feature a huge number of pages and subpages.

mahmoud791

Custom Page Attributes

Customize the parent page dropdown in the page attributes meta box to show only top-level ones with no parent.

enomoto celtislab

Hierarchy Pages Nav

Document hierarchy pages like a book and provide easy navigation between pages.

WebHostingHero

<p>This plugin displays a drop down menu in the admin dashboard that allows you to filter the page list by their parent page. No configuration is necessary.</p>


Parent Page Filter

It's a simple plugin and does the job, but only if WP_DEBUG is disabled.
The two main issues I have with this plugin are:

It assumes that $_GET['post_type'] exists and/or is set, when it mightn't, which throws PHP warnings and sometimes actually halts page load, here and here.

Not ready for translation

(I am happy to patch by the way, a GH repo would be nice)



Alternatives to Parent Page Filter

Top alternatives