Is it permissible for a father to estimate a suitable monthly amount for his children's maintenance and deduct it from the value of his stolen money if the children's mother refuses to provide him with what she has spent on them, knowing that he wishes to give them the minimum legitimate maintenance and avoid falling short in his duty to God?

If the children have no money, their maintenance is obligatory upon the father, even if they are in the mother's custody or the father does not see them. This maintenance is estimated based on sufficiency. The father is not permitted to offset their maintenance with money that the mother owes him, because the children's maintenance is an independent right for them. The mother has a greater right to custody unless her right is forfeited, such as by her marriage. It is not permissible for the one who has custody to prevent the other party from seeing their children.