Is a marriage, contracted without the knowledge of the family and with the testimony of a taxi driver who claimed to be the maternal uncle, considered invalid after six years and the birth of two children?

Marriage is not valid except with a guardian (wali), based on the saying of the Prophet, peace and blessings be upon him: "There is no marriage except with a guardian," and his saying: "Any woman who marries without the permission of her guardian, her marriage is invalid." Your father is your guardian, not your brother. Therefore, your marriage is invalid and must be annulled. The lineage of the two children is established from their father. The contract can be renewed correctly in the presence of the guardian (the father) and two upright Muslim witnesses.