How can I make AWS Bedrock knowledge bases provide citation for URL in metadata?

AWS Bedrock knowledge bases currently cite information by linking to the S3 objects (e.g. Word document) it was retrieved from.

This isn’t useful in my case, as user’s cannot access the S3 objects.

However, for each S3 object, there is associated metadata that includes a URL that should instead be used for citation.

Can this be achieved?