Is it Islamically permissible for a widow to continue receiving her deceased husband's pension after marrying another man without a contract, for the purpose of spending it on her orphaned children?

If the pension is a grant and a donation, then the conditions of the granting entity must be referred to. If it is granted to the widow on condition that she does not remarry, then it is not permissible for her to use deception and take it if she remarries, because that is cheating and consuming wealth unlawfully. If it is for the orphans, then it belongs to them whether their mother remarries or not. However, if the pension was deducted from the deceased’s salary, then it is a right for all heirs, to be divided according to the laws of inheritance, and the wife is entitled to her share of it even if she remarries.