According to the current regulations, there is no explicit provision on how to prove that money is not used for families, so please collect evidence according to your own actual situation and relevant regulations.
Relevant regulations: Interpretation of the Supreme People's Court on Several Issues Concerning the Application of the Marriage Law of the People's Republic of China
Article 23
The people's court shall not support the creditor's claim against the debtor's spouse for the personal debt incurred by one party before marriage. Except where the creditor can prove that the debt is used for the married family to live together.
