Is it permissible for the husband to deduct 4,000 from his father's outstanding debt, or must he pay off the debt first and then settle his account? And is it permissible to fast Ramadan while there is a dispute with relatives?

If the husband owes a debt to his wife's father, and the father owes a similar debt to the husband, it is permissible for the husband to deduct the debt he owes to his wife's father against the debt he is owed by the father. This is known as offsetting (set-off). However, if the husband pays a debt on behalf of his wife's father without the father's permission, there is a jurisprudential disagreement among the schools of thought regarding the possibility of reclaiming this debt. The Malikis and Hanbalis permit reclaiming the debt if the intention was not to donate, while the Shafi'is and Hanafis do not permit it. Those who permit reclaiming the debt stipulate the intention of recovery, and some of them stipulate that the debtor refrained from paying.