Is it obligatory to repay the sums of money that the father took from some of his children to cover the tuition fees of another son, knowing that this son did not receive the money directly from his siblings?

A father is permitted to take from his son's wealth under certain conditions: that taking it does not harm the son, that the son does not need it, that the father only takes what he needs, and that the money taken is not given to another son. Therefore, if your father took from your brothers' money and gave it to you, his action is impermissible. If what your brothers paid was a donation, they are not allowed to reclaim it. However, if it was a loan or taken without their consent and that is proven, then it becomes a debt to be repaid from your father's estate before distribution. Your brothers do not have the right to demand these funds from you because you did not take them directly from them. It is advisable to maintain kinship ties and to resolve the dispute with gentleness.