Hi,
Thank you for contacting us and I'd be happy to assist.
Your observation is correct and the Blocks based views, currently can't be nested within one another.
To achieve this, you'll need to create views, using the Classic editor, and here are the steps:
1. Please go to WP Admin -> Toolset -> Settings -> General and make sure that "Show both the legacy and Blocks interface and let me choose which to use for each item I build" option is selected for the "Editing experience" field.
2. Next, go to WP Admin -> Toolset -> Views and create a new post view "View to show companies related to a city".
This view will be set to show "Companies" posts, with a post-relationship filter, with respect to the "Cities Companies" relationship to show results related to the Post where this View is shown.
( screenshot: hidden link )
In the "Loop Editor" section of this view, you can select the desired format in which you'd like to show this list of related companies.
3. You'll create another post view "View to show opinions related to a company".
This view will be set to show "Opinions" posts, with a post-relationship filter, with respect to the "Companies Opinions" relationship to show the results that are related to the current post in the loop.
( screenshot: hidden link )
In the "Loop Editor" section of this view, you can select the desired format in which you'd like to show this list of related opinions.
4. Once both these views are ready, you'll add the shortcode of the parent view ( "View to show companies related to a city" ) in the content template for the single city posts:
( ref: https://toolset.com/documentation/programmer-reference/views/views-shortcodes/#wpv-view )
[wpv-view name="view-to-show-companies-related-to-a-city"]
And the shortcode for the child view ( "View to show opinions related to a company" ) in the loop of the parent view, so that it is used a nested view:
( screenshot: hidden link )
[wpv-view name="view-to-show-opinions-related-to-a-company"]
I hope this helps and please let me know if you need any further assistance around this.
regards,
Waqar