Does divorce occur with the statement "Consider your sister divorced" if there was no intention of divorce, and is it considered a third divorce given the presence of two daughters and a pregnancy, especially since the words were uttered unintentionally during an argument with the wife's brother?

It is not a condition for divorce to take effect that the wife be addressed directly. Divorce takes effect as soon as the husband utters it, as long as he is aware and acting voluntarily, unless his anger reaches the point of insanity.

If your statement to your wife's brother, "Do you see your sister as divorced?" was a question, then no divorce has occurred. However, if it was an declaration of divorce, then divorce has occurred.

It is advisable to consult the Sharia court or scholars to decide on the matter, and to exercise forbearance, patience, and avoid anger.