My ex wife just inherated a substantial amount of money from her brothers death but has not reported it tochild suport. How can I prove this to the court?

You can try to get her records on it. But Im not sure that she had to report it. Mostly it depends on the state you filed in and how the laws of that state are written.

You shouldn't throw around terms like fraud without knowing the law. There may not be any requirement to report it. Local laws and whether he is up to date on support are key factors.

If you think it should be reported, file for a change in support and subpoena the probate court records.