If you have located additional documents that you did not have before, you need to produce such documents in a supplemental document production response. Otherwise, the defendant landlord will undoubtedly object to the admission of such documents as evidence at the time of trial, and/or file a motion in limine to preclude their admission.
Frank W. Chen has been licensed to practice law in California since 1988. The information presented here is general in nature and is not intended, nor should be construed, as legal advice. This posting does not create any attorney-client relationship with the author. For specific advice about your particular situation, consult your own attorney.
Mr. Chen is correct. If you have additional documents, then you should do a supplemental response and provide copies of the documents.
You can, in some cases, withhold documents and use them for impeachment purposes at trial, but I do not recommend that someone without legal training do so. If you are wrong, they could be excluded.
If you withhold requested documents during the discovery process, you can be prohibited from relying on those documents at the time of trial.
Answers on this site are only intended to provide general information. No attorney-client relationship is intended. Specific legal advice is only provided after a personal meeting in which detailed information about a client's particular circumstances and goals are obtained.