Jerusalem Talmud Yevamot 3.5

משנה: שְׁלֹשָׁה אַחִין שְׁנַיִם מֵהֶן נְשׂוּאִים שְׁתֵּי אֲחָיוֹת וְאֶחָד נָשׂוּי נָכְרִית. מֵת אֶחָד מִבַּעֲלֵי אֲחָיוֹת וְכָנַס הַנָּשׂוּי נָכְרִית אֶת אִשְׁתּוֹ וָמֵת. שְׁנִיָיה יוֹצִיא מִשּׁוּם אֲחוֹת אִשְׁתּוֹ וְרִאשׁוֹנָה מִשּׁוּם צָרָתָהּ. עָשָׂה בָהּ מַאֲמָר וָמֵת נָכְרִית חוֹלֶצֶת וְלֹא מִתְיַיבֶּמֶת.

MISHNAH: Of three brothers, two are married to two sisters and one to an unrelated woman. One of the sisters’ husbands died, the husband of the unrelated married his widow, and died. [The dead brother’s] second [wife] leaves as his wife’s sister, the first one as her co-wife. If he had “bespoken” her, the unrelated woman performs ḥalîṣah but cannot have levirate.

הלכה: שְׁלֹשָׁה אַחִין שְׁנַיִם מֵהֶן נְשׂוּאִין לִשְׁתֵּי אֲחָיוֹת כול׳. בֵּין רַבָּנִין בֵּין רִבִּי שִׁמְעוֹן מוֹדִין בָּהּ. כְּרַבָּנִין צַד שֶׁקָּנָה מַאֲמָר כְּנֶגְדָּהּ אָסוּר בַּצָּרָה. וְצַד שֶׁלֹּא קָנָה בָהּ מַאֲמָר כְּנֶגְדּוֹ אָסוּר בַּצָּרָה. לְפִיכָךְ חוֹלֶצֶת וְלֹא מִתְיַיבֶּמֶת. כְּרִבִּי שִׁמְעוֹן קָנָה מַאֲמָר שְׁתֵּיהֶן מוּתָּרוֹת. לֹא קָנָה מַאֲמָר הָרִאשׁוֹנָה אֲסוּרָה וְהַשְּׁנִיָּה מוּתֶּרֶת מִסָּפֵק חוֹלֶצֶת וְלֹא מִתְיַיבֶּמֶת.

HALAKHAH: “Of three brothers, two are married to two sisters,” etc. Both the rabbis and Rebbi Simeon will agree in this case. For the rabbis, the part of the co-wife parallel to that which “bespeaking” acquired [in the widow] is forbidden. Also, the part of the co-wife parallel to that which “bespeaking” did not acquire [in the widow] is [still] forbidden. Therefore, she performs ḥalîṣah but cannot have levirate. Following Rebbi Simeon, if “bespeaking” acquires, both are permitted. If “bespeaking” does not acquire, the first is forbidden but the second permitted. Because of the doubt, she performs ḥalîṣah but cannot have levirate.