How can the second wife and her children claim their right to inheritance if the husband kept his marriage to them a secret and did not disclose it to his family and first wife before his death?

If the second marriage is religiously lawful but not officially documented due to circumstances preventing it (such as residing in a Western country), the second wife and her children can prove the marriage through the presence of the guardian (wali), witnesses, public announcement, a written document from the husband, or the registration of the children in his name. After that, the wife presents the evidence to the Islamic center, which then presents it to the deceased's family to establish her rights and her children's rights to the inheritance. The first wife and her children must comply, and they are warned against severing ties of kinship and consuming the rights of others, especially orphans, because consuming an orphan's wealth is a grave sin.