Is it permissible to take out an interest-bearing loan to pay off a debt owed by my wife's brother, which resulted from an unauthorized withdrawal from his inheritance, in order to avoid family problems, especially since I am experiencing financial hardship and have many debts?

Borrowing with usury is one of the gravest sins and one of the seven destructive evils. It is not permissible to engage in it except in cases of extreme necessity, such as fear of perishing. Repaying a debt is not considered a necessity that permits usury. And whoever fears Allah and relies upon Him, He will provide him with a good provision and help him repay his debt. Allah Almighty says: "And whoever fears Allah - He will make for him a way out And will provide for him from where he does not expect. And whoever relies upon Allah - then He is sufficient for him."