Hi there,
Thank you for contacting us and I'll be happy to assist.
From your message, I understand that you'd like to attach the featured image from the related post when a new post is created or updated from the admin area.
If this is correct, you'll need a custom function for this, since this feature is not available, out-of-the-box.
As much as we would like to help, 1-1 code customization is beyond the scope of support that we provide. But, we do our best to guide in the right direction, whenever possible.
To execute a custom function for this, when a post is created or updated from the admin area, you can use the hook "save_post":
https://codex.wordpress.org/Plugin_API/Action_Reference/save_post
To get the ID of the related post, you can use the Toolset function "toolset_get_related_posts":
https://toolset.com/documentation/customizing-sites-using-php/post-relationships-api/#toolset_get_related_posts
To get the ID of the featured image from that related post, you can use the function "get_post_thumbnail_id":
https://codex.wordpress.org/Function_Reference/get_post_thumbnail_id
As the last step, to set that same image as the featured image of the current post, you can use the function "set_post_thumbnail":
https://developer.wordpress.org/reference/functions/set_post_thumbnail/
Note: You'll find a good example of how these functions can be used together in this reply:
https://stackoverflow.com/a/49126804
I hope this helps and for more personalized assistance around custom code, you can also consider hiring a professional from our list of recommended contractors:
https://toolset.com/contractors/
regards,
Waqar
