311. Women and Minors

45:22 If women ate with men who are obligated in a zimmun, the women also become obligated and they must hear (and answer – MB 199:17) the blessing of the zimmun. A minor is not included in a zimmun until he has reached the age of thirteen years and one day. He may then join a zimmun and we are not concerned to check whether or not he shows the physical signs of maturity. (He must, however, show the signs of maturity to lead a zimmun. If we know for a fact that he does not yet have the signs of maturity, he may not join a zimmun. – MB 199:27.)

45:23 One who does not recite the Shema or who publicly violates the Torah is not counted for a zimmun. A convert counts in a zimmun and he says the words “Who gave to our forefathers as an inheritance.” This is because the Torah describes Abraham as “a father of many nations” (Genesis 17:5), which is understood to mean that he was once father only to Aram but he became the father of people from all nations.