Related for Kiddushin 146:13

A man who went with his wife to the land beyond the sea, and he, his wife and his children came back, and he said: "The wife that went with me to the land beyond the sea—this is her and these are her children"—he needs to bring evidence neither about her nor about the children [to prove that they are his and hers]. "[The wife that went with me...] died, but here are her children"—he needs to bring evidence about the children but doesn't need to bring evidence about the wife. A woman/wife is believed when she says, "These are my children". (The following translated from the Ehrfurt manuscript:) A man is believed when he says: "The wife that I married in the land beyond the sea—this is her and these are her children"—he needs to bring evidence neither about the wife, nor about the children. "[I married a wife there but] she died, and these are her children"—he needs to bring evidence on both the wife and the children. A woman is believed when he says "These are my children."