Once you have your files together for each independent contractor or if you have strong evidence that these people are independent contractors, the next phase is preparing your contractors to be contacted and potentially interviewed by the EDD auditor. You need to be careful here, very careful, because you are walking a fine line.
However, best practices in California dictate that you should gather about five people that are your best sources for 1099 information and create a reference sheet for the tax auditor to reach out and contact them.
The reaction that you are going to get from the tax auditor will be a mixed bag. Some auditors appreciate the help and some will buck a little because it appears that you might be trying to control how you are running their audit.