You need to hire an attorney in CA. Immediately.

How can you be "added" to a judgment? They have to name you as a defendant in the civil action, serve you, and do the entire case to trial and judgment. I don't understand how they can "amend" a judgment. That needs to be researched obviously. Nobody can just add a third party who was never sued to a judgment by "amendment".

Perhaps someone here knows CA law but I would be surprised if anyone has direct knowledge, especially based on the lack of detail in your posting.