The appeal is a completely new trial. You should pretend as if the case in small claims court never happened. The judge won't care what happened there, and may cut you off if you talk about it.
I doubt the judge hearing the appeal will review papers filed in the small claims court action. He will rely only on what is filed and presented during the appeal. If your addendum is only filed in the small claims action, you should take appropriate steps to have it filed before the appellate judge in order to make sure it is considered. The Court clerk, however, may be able to tell you whether the small claims file is actually transferred to the appellate judge, or whether you should re-file it in the appellate proceeding.
Best of luck to you.
No, an appeal of a small claims judgment is not really an appeal but rather a trial de novo (new trial). Whatever happened in the original trial is not relevant. You should treat the appeal trial as a completely new trial. The judge will review the Plaintiff's Claim and any addendum thereto prior to the commencement of the trial de novo.
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 for a particular case. This Avvo.com posting does not create any attorney-client relationship with the author. For specific advice about your particular situation, please consult with your own attorney.
In my experience, the judge knows the underlying decision. Be prepared as you were originally, and if you have new material/evidence etc, have it ready.