Jerusalem Talmud Yevamot 3.8

משנה: שְׁלֹשָׁה אַחִין שְׁנַיִם מֵהֶן נְשׂוּאִין שְׁתֵּי אֲחָיוֹת וְאֶחָד נָשׂוּי נָכְרִית. גֵּירַשׁ אֶחָד מִבַּעֲלֵי אֲחָיוֹת אֶת אִשְׁתּוֹ וּמֵת הַנָּשׂוּי נָכְרִית וּכְנָסָהּ הַמְגָרֵשׁ וּמֵת. זוֹ הִיא שֶׁאָמְרוּ וְכוּלָּן שֶׁמֵּתוּ אוֹ שֶׁמֵּיאֵינוּ אוֹ נִתְגָּרְשׁוּ אוֹ שֶׁנִּמְצְאוּ אַיְילוֹנִיוֹת צָרוֹתֵיהֶן מוּתָּרוֹת.

MISHNAH: Of three brothers, two are married to two sisters and one to an unrelated woman. If one of the sisters’ husbands divorced his wife, when the one married to an unrelated woman died and the divorcer married her and then died, that is what they said: Of all of these, if they died, or repudiated, or were divorced, or turned out to be she-rams, the co-wives are permitted.

הלכה: שְׁלֹשָׁה אַחִין כול׳. גֵּירַשּׁ. רִבִּי חַגַּיי בְשֵׁם רִבִּי זְעִירָא. לֹא סוֹף דָּבָר בְּשֶׁגֵּירַשּׁ וְאַחַר כָּךְ כָּנַס. אֶלָּא אֲפִילוּ כָּנַס וְאַחַר כָּךְ גֵּירַשּׁ. הָדָא הִיא דְּתַנִּינָן שֶׁאִם מֵתוּ אוֹ נִתְגָּרְשׁוּ צָרוֹתֵיהֶן מוּתָּרוֹת.

HALAKHAH: “Of three brothers,” etc. Rebbi Ḥaggai said in the name of Rebbi Ze‘ira, not only if he divorced and after that married, but even if he married and after that divorced. That is what we had stated: “Of all of these, if they died or were divorced, their co-wives are permitted.”

אָמַר רִבִּי יוּדָן. אַף רִבִּי לִעֶזֶר מוֹדֶה. אָמַר רִבִּי יוֹסֵה. וְיֵאוּת. אִילּוּ מִי שֶׁהָיוּ לוֹ בָנִים וּמֵתוּ וְאַחַר כָּךְ מֵת הוּא שֶׁמָּא אֵין אִשְׁתּוֹ זְקוּקָה לְיִיבּוּם. תַּמָּן וְהוּא שֶׁהָיוּ לוֹ בָנִים בִּשְׁעַת מִיתָה. וְהָכָא וְהוּא שֶׁתְּהֵא צָרָה לְאַחַר מִיתָה.

Rebbi Yudan said, even Rebbi Eliezer agrees. Rebbi Yose said, that is correct. Because, if somebody had children but they died before he died, is his widow not a candidate for levirate? There, if he had children at the moment of death. Here, if they were co-wives after his death.