fancyfiber

Requires the plug-in <a href="https://wordpress.org/extend/plugins/advanced-custom-fields/" title="Awesome plug-in to manage custom fields" rel="ugc">Advanced Custom Fields</a>.
This is a very basic add-on to allow the ability for relationship fields that are associated with a single related item, to be able to add a new 
item to the related item without leaving the post/page you are currently editing. Uses a colorbox pop-up to open the add new post window with very 
limited options.
Usage:
<ul>
<li>Install the plug-in (standard WordPress installation)</li>
<li>Set up a relationship field with only one related item (standard Advanced Custom Field configuration)</li>
<li>Add or Edit a post with the relationship and the new Add New button will show up on the relationship field</li>
<li>Click the Add New button to open Colorbox add new post for the related item</li>
<li>Click the publish button and the new item will be added (or click the X button to cancel) and the Colorbox will close</li>
<li>The newly added item will be available for selection in the relationship list</li>
</ul>
This plug-in was developed for <a href="http://www.tanabi.com" rel="nofollow ugc">Tanabicom, LLC</a> and <a href="http://www.5dspectrum.com" rel="nofollow ugc">5D Spectrum, Inc</a> by <a href="http://hosting.fancyfiber.com/design/" rel="nofollow ugc">Fancy Fiber Designs</a>

ACF Single Relationship Add New

Add a new related item while editing a post, without leaving the current post.

Divi Coding

Divi ACF Object Loop is an extension of the Divi theme by Elegant Themes. It includes a visual builder module that can output the content of an Advanced Custom Field (ACF) Post Object or Relationship field.
This module can be utilized on a single page, post, custom post type, or any Divi Builder template to enhance your content display. You have the freedom to choose from a range of options, including displaying post-feature images, titles, excerpts, and permalink data. The module has been designed to be responsive and offers grid display options with column and gap control settings.

CT Divi ACF Object Loop

Add a new module to the Divi collection to show ACF Post Object or Relationship field info in a grid.

ACF Single Relationship Add New vs CT Divi ACF Object Loop