How to enable the originalsourcesystemreference number child field in adaptive search?

Summary:

I'm using the REST API endpoint of adaptive search and I want to expose the Original Source System Reference field of an account from contact entity. The account is at child level from the contact entity.

Content (required):

Here is the adaptive search configuration:

Version (include the version you are using, if applicable):

23A

Code Snippet (add any code snippets that support your topic, if applicable):