Is it permissible for a girl to conceal from her family the fact that a suitor is already married, in order for them to marry her to him lawfully?

Allah has permitted a man to marry up to four women, provided he deals justly with them.

The suitor is not required to inform the bride's family of his previous marriage, and the lack of disclosure does not affect the validity of the marriage.

Similarly, the fiancée is not required to inform or seek permission from her parents. However, a guardian is better able to assess the suitor's suitability, as a woman's emotions may sometimes overpower her intellect.

A group of jurists are of the opinion that a father with the right of ijbar (compulsion) is not considered to be preventing marriage (ʿāḍil) by rejecting a suitor, due to his compassion for his daughter and her lack of knowledge regarding her own best interests.

Therefore, it is preferable not to agree to a marriage without the family's knowledge of the suitor's situation, as this leads to a safer outcome.