WebHostingHero

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.

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)



Works ok-ish, needs a few tweaks

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

Julio Potier

You can now add passwords as many as you need on every protected page.
Why? Because you can protect page and give your client a personnal password, not just a random pasword or everyone.
Option: If you are logged as admin or the page’s author, you won’t need to enter password.
Option: If you set a list of child pages, just change any password (parent page or any child) and all the password for the hierarchy will be updated!

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.

Parent Page Filter vs Multiple Passwords for Protected Pages