Am I sinful for marrying another woman and having two children with her without informing my family, knowing that the marriage contract is documented in the country of residence but not through the Egyptian embassy?

The parents do not have the right to order their son to divorce his righteous wife, and he is not obligated to obey them in this matter. The husband did well by informing his second wife about the existence of another wife and children. It is recommended to document the marriage contract at the embassy or have trustworthy individuals witness it, to ensure rights and prevent disputes.