Look how much he owed and how they paid it at that time. Generally speaking, the debts of adults are borne independently, and family members do not need to bear joint and several liabilities. However, since he is your father-in-law, you have property to inherit. So, you are responsible for repayment. If you refuse to pay back, there is another way, that is, the creditor will seize your father-in-law's property by suing the court and repay the property to the creditor after auction. But not all will be sealed, only the value that needs to be repaid. For example, your father-in-law owes someone 50 thousand, and his property value is100 thousand. After paying back 50 thousand, you will inherit the rest.