How to customize reply when information is not found?

[myusoutharm]

For the "bring your own data" use case, how to customize the default reply when no information is found? The default reply is "The information about x is not available in the retrieved documents. Please provide another query related to the content in the documents for assistance.". Need to customize it by adding a link to a form that users can submit/suggest documents for a question, and the attachment will be uploaded to Blob, which will be indexed daily.

Thanks.