What I'm also saying though is that although the F.I.L owes the CC Co., the wife still owes her father - even if she was dismissed - fairly or otherwise. The apparent agreement to repay the 11k is probably not part of the employment remuneration package. How would we know this?
Well, apart from the terms and conditions that the employee must receive from the employer, the credit card statement will show the nature of the purchases made. If it's fuel for the company car, or other work expenses, that may indicate (in the absence of written proof), that the use of the card was a benefit in kind - very likely to be subject to income tax though!!! If it was used for food, holidays, train or cinema tickets, etc etc, it would show that the credit card was being used for purposes unrelated to her employment.
So my feeling is that both parties will have to pay their respective creditors.