Unable To Define Or Edit The Relationship Between Published Data Source (New Data Model Added From 2020.2)

Issue

Unable to create or edit relationship between published data sources

Environment

Tableau Server 2020.2 and later
Tableau Desktop 2020.2 and later
Tableau Cloud

Resolution

Workaround

The data source relationship needs to be edited before publishing.
1. Download the content (separately published data source or a workbook with embedded data source) from Tableau Server
2. Open the content in Tableau Desktop
3. Select the data source page, and enter the credentials when asked
User-added image

Cause

The ability to define/edit relationship on published data sources is not a feature built in the product as described in Online help below.

Requirements for relationships

Additional Information

To voice your support for the future implement of this feature, please vote on the following idea:

Enable relationships on published datasets

To confirm the relationships, you need to open the edit page of the data source, and since a published data source is already considered "completed and shared", you cannot check it directly on the Tableau Server-side currently. The following knowledge base contains the relevant specifications.
Editing a Published Data Source On Tableau Server