There is a sight called
Family Law Web Guide
On this sight are people who are top guns on legal issues and also CSA legals, you may want to go there and pose your question.
I think they would answer your question to a finite point.
But if you need support in any other way we are your guy's, FLWG lacks a little in this area so if we can help you make sure you come back.
You should also ask them about non disclosure on her paperwork and it's effects on CSA as well as FTB A&B.
All the best hope to hear from you soon OH and by the way Welcome to the forum.
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I never offer advice just options that might not have been seen.