Kidushin4: 11
,,אִשָּׁה נָשָׂאתִי בִמְדִינַת הַיָּם הֲרֵי הִיא זוֹ, וְאֵלּוּ בָנֶיהָ” — מֵבִיא רְאָיָה עַל הָאִשָּׁה, וְאֵינוֹ צָרִיךְ לְהָבִיא רְאָיָה עַל הַבָּנִים.  ,,מֵתָה, וְאֵלּוּ בָנֶיהָ” — צָרִיךְ לְהָבִיא רְאָיָה עַל הָאִשָּׁה וְעַל הַבָּנִים.
[If one says:] “ I married a woman overseas; this is she and these are her children,” he must bring proof concerning the woman, but he need not bring proof concerning the children.  [If he says:] “ She died, and these are her children,” he must bring proof concerning the woman and the children.