Display posts from ACF Reverse Relationship using Post Blocks Adv widget

Before configuring the Post Blocks Adv widget, let's first see what actually is a Reverse Relationship?

Let's consider an example of Books and Authors. One Author can write many books. Similarly, a book can be written by more than one Author. Therefore, we can set up a direct relationship between Books and Authors and can display the details. But what if you want to display the details of all the books written by a specific author on the Author Detail page? We can get data for this reverse query using the Reverse Relationship feature.

This will require you to create a Relationship Field for Post/Page/CPT using the Advanced Custom Fields (ACF) plugin. 

You can find more details about the ACF - Relationship Field here

Follow the steps below to show Posts from Reverse Relationships on a Single Post Layout. Drag the "AE - Post Block Adv" widget to the desired location in your AE Template. Do the following configuration: 

Under the Layout Section:

• Skin: Select the layout style to display the post blocks.
• Block Layout: Select the Block Layout you have created to use in this widget. Learn more about creating block layouts.

Under the Query Section, do the following configuration.

• Source: Relationship
• Relationship Field: Name of the Relationship Field that you have created in ACF.
Also, set "Return Format" to "Post ID." By default, it is set to Post Object. 
• Reverse Relation: Enable the Reverse Relation option, to get reverse relationship data.
• Do rest of the settings like order by, layouts, etc., as required.
• See the following screenshot for the configuration setup.