Legal Question in Family Law in California

What you are asking for is way too complicated to explain in a web bulletin board format. The way you serve a subpoena for business records is fairly simple. Every corporation has an agent for service of process who can be found in the Secretary of State's website. You prepare a subpoena and have it served on the agent for service of process. Beyond that, though, how to ask for and obtain specific evidence and what documents you need for your case is impossible to answer here with no information about the situation or the case.