Is a child born from an invalid 'urfi marriage, prior to the completion of a valid Shar'i marriage, considered illegitimate and unblessed, even if acknowledged by the father and repentance has occurred?

An unregistered marriage (zawaj 'urfi) without a guardian (wali) or public declaration (ishhar) is invalid, and it is not permissible to continue in it. If the couple believed this purported marriage to be permissible, then the pregnancy is attributed to the one who engaged in this alleged marriage, and the sexual intercourse is considered an act of شبهة ( شبهة al-wat', dubious intercourse) through which the child is attributed to him and inherits from his father. However, if it was purely a violation of Allah's sacred limits without believing it to be permissible, then the pregnancy is a child of fornication (ibn zina) and is not attributed to the one who committed the act, according to the majority of scholars.