There is a famous case that happened about ten years ago where the wife bought a lottery ticket while married to her husband. She won the lotto after they separated and didn't tell her husband. Her was awarded the entire lottery winnings. However, you have to prove the asset exists and that the other party knowingly concealed he asset. It sounds like you will need to hire at least one expert to help you, perhaps more. This may include a private investigator, an accountant, and an attorney.