What is the amount of child support after the separation of the spouses, and what is the ruling of Islamic law regarding the custody of children over ten years of age if their mother divorces their father, then marries another man, then divorces him, knowing that her work requires her to be absent from them for long periods?

The maintenance of children is obligatory upon the father to the extent of sufficiency, and it does not change with the mother's divorce. If the children have their own money, the father should spend on them from it in a reasonable manner; otherwise, he is obligated to spend on them. The mother has the primary right to custody unless she remarries. If she remarries, her right is forfeited and transfers to the next deserving person. If the mother is divorced by her second husband, whether revocably or irrevocably, her right to custody returns according to the Shafi'i and Hanbali schools of thought. According to the Hanafis, it returns only in the case of an irrevocable divorce, while according to the Malikis, it does not return. Children after the age of seven are given a choice.