Validity of the marriage contract despite hiding some matters when concluding it
Does hiding any significant information (a previous marriage or having children from a previous marriage) from the Waliy (a legally accountable person acting for a woman regarding marriage) breach the marriage contract even though the fiancée already knows such information and agrees to marry the man for his righteousness, social status and good manners?
My understanding is that the fiancée has already been informed of the personal circumstances of her fiancé such as his previous marriage and she does not care whether he divorced his first wife, she died or he is still keeping her as a wife, (Part No. 18; Page No. 403) and whether he has children from such marriage or not. She agreed to marry that man for his righteousness, good manners and social status and therefore she hid this information from her Waliy as the fiancé did, lest the Waliy should oppose the marriage. If the reality is as you mentioned, hiding this information does not violate the marriage contract since it is concluded by the Waliy and the bride agrees to it as the groom's religious commitment is agreeable to her. Also, it is the wife's right to know this kind of information; not the Waliy's. May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.