WenZe

Category Parent Children Selector is a WordPress plugin that helps you in selecting parent-children categories.
Features include:
<ul>
<li>Button to select all categories. </li>
<li>Button to select all categories including children categories. </li>
<li>Button to select first level of children categories only. </li>
<li>Button to select parent and all its children categories under its sub categetory. </li>
<li>Auto select parent categories when a sub category is selected.</li>
</ul>

Category Parent Children Selector

Helps you in selecting parent-children categories.

Alex Mills

When adding a page, category, or any hierarchical custom post type or taxonomy to your navigation menu (Appearance → Menus), this plugin allows you to optionally automatically add all descendants (children) of that menu item as submenu items.
In short, you’ll no longer have to manually maintain submenus when you add a new child page to your site.

Add Descendants As Submenu Items

Still works great. Much better than Gecka Submenu - it doesn't break the layout on the menu screen and there's no unnecessary pro version upsell.  I hope this is updated at some point because its age is hiding it from WP's search results.



Works great and it's clean

Automatically all of a nav menu item's descendants as submenu items. Designed for pages but will work with any hierarchical post type or taxonomy …

Category Parent Children Selector vs Add Descendants As Submenu Items