You need to speak to an EXPERIENCED family law attorney, who will set the opposing counsel right, and get discovery ORDERED. This does not sound like it's going to be a "do it yourself" job, and getting the right attorney now may mean thousands of dollars in difference in support later.
You are in a disadvantage not having a lawyer. Paternity not simple. And you are in Orange County. So hire a family law attorney.
An item or request or right is "at issue" when relief in one way or another is sought based on that. So if support is not sought then it is not an issue. However discovery is extremely complicated and just because something is not "at issue" does not make it an absolute rule.
Can not possibly explain all the intertwined rules of discovery in any short answer and you are sailing in unchartered territories in discovery and paternity in Orange County. . Good luck.
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You can go to your local Dept, of Child Support Services to get parentage and support established. That office does not represent you, but their job is to get the right amount of support. Further, the original support order can be made retroactive to the date of filing the petition,.