Have resided together for at least six months prior to filing an Affidavit of Domestic Partnership. This certificate shall be presented to a judge of a court of record in the county in which the witness resides, or the county in which he is found if not a.12 stated in the affidavit. The affidavit is admissible in evidence. This affidavit documents the cohabitation of a couple for over six years without being legally married. One out-dated case indicates that an instruction on what constitutes corroborating evidence is adequate if given in the words of Section. l.839. File Supplemental C Affidavit of Certification Form. Supplemental C Affidavit of Certification for the City of Oakland. We are executing this affidavit to attest to the foregoing facts and for the purposes of contracting marriage without the need of securing the marriage license. Click here to book an appointment.