Sentence examples similar to and return to the undersigned from inspiring English sources

The phrase "and return to the undersigned" is correct and usable in written English.
It is typically used in formal correspondence, often in legal or official documents, to indicate that something should be sent back to the person who signed the document.
Example: "Please complete the attached form and return to the undersigned at your earliest convenience."
Alternatives: "and send it back to me" or "and reply to the signer."