A [boy] nine years and one day old who cohabited with his yevamah, and then cohabited with her co-wife —- he has disqualified [them] to himself. R' Shimon says: He did not disqualify.  [If] a [boy] nine years and one day old cohabited with his yevamah and [then] died, she performs chalitzah, but may not be taken in yibum. [If] he married a woman and [then] died, she is exempt.

A [boy] nine years and one day old who cohabited with his yevamah, and [then,] after reaching adulthood, [he] married another woman, and died —- if he was not intimate with the first one after reaching adulthood, the first one performs chalitzah but may not be taken in yibum, while the second one may either perform chalitzah or be taken in yibum. R' Shimon says: He may perform yibum with whichever he prefers, and must [then] perform chalitzah with the other one.  [It is] the same whether he is aged nine years and one day or aged twenty and has not grown two hairs.