Please incorporate the other answer that I gave you with this answer.
Your daughter needs to get all the proof that she can that she reimbursed X for her credit card
usage on his card. If she was authorized to use the card, ultimately, much responsibility for this debt will rest on X and not on her. X can bring an action against her, but if she proves that she had authorization and that she paid X for her charges, she should not have any liability as it was not her card. The cc company wants to collect from as many people as possible; however, if X let her use the card, then X is primarily responsible as it is X's card.
Now to answer your questions: people do not go to jail in the US because of cc debts. She will create a payment plan with the companies, or she will declare bankruptcy. She will negotiate a payment plan with the companies or else she may find a legal way to escape the debts. The same thing is true for X since X is the cardholder. Please let me know if you have further questions.
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