Michelle Blanchette

Grouped Content helps you manage and access your hierarchical pages (including hierarchical custom post types) naturally and automatically. All it takes is the simple action of setting a parent page. (Which you are probably already doing!)
<h4>Enhanced Page Management</h4>
With Grouped Content, you’ll be able to access pages faster, quickly generate new draft pages in bulk, and better visualize your site’s hierarchy. Additionally, you’ll be able to see overview information of each page group. This can give you insight into which content groups are the largest or have the most drafts.
<h4>Features</h4>
Grouped Content is light and simple with a few powerful features. You can get started immediately all while keeping control of your site’s pages with these main features:
<ul>
<li>Groups Admin Page. View hierarchical pages and group statistics in an easy-to-navigate, distraction-free area.</li>
<li>Page Relatives Metabox. Access parent, sibling, and child pages immediately upon setting a parent page.</li>
<li>Content Generator. Quickly add new draft pages and automate menu creation to efficiently create new groups of content and navigation for your site.</li>
</ul>

Grouped Content

Provides easy access to hierarchical posts' parent page, sibling pages, and child pages in wp-admin.

Yudhistira Mauris

This plugin helps you create a series of posts. It creates a new taxonomy named ‘series’ (can be modified via filter, see FAQ). There is no setting needed for this plugin. Once it is installed, assign posts you want to group as a series via post editor.
The plugin also creates a posts navigation on posts that belong to a certain series. See screenshots for the examples.

Easy Post Series

Works beautifully and doesn't have a sucking frontend design, as other similar plugins do!

Grouped Content vs Easy Post Series