Is the father obligated to provide for his children from his divorced wife at the same level as he provides for his children from his new wife, and is he sinful if he does not? And does the value of the maintenance change with changing financial or economic circumstances?

The fatwa adopted by us dictates the obligation of equality among children (males and females) in gifts and endowments, whether they are from one wife or multiple wives, unless some children have a need that necessitates preferring them. As for expenses, equality is not obligatory therein; rather, what is obligatory is sufficiency according to the child's situation, the time, and the country. This includes educational expenses which are necessary.