Kiddushin 4:11

If a man claims that he married a woman overseas and that this is her and these are her children, he must prove the woman’s lineage but not that of the children. If he says he married a woman who died and these are her children, he must prove lineage both for her and for them.

Kiddushin 4:12

A man may not be alone with two women but a woman may be alone with two men. Rabbi Shimon says that a man may be alone with two women when his wife is with him, even sleeping at an inn, because she will keep an eye on him. A man may be alone with his mother and his daughter, even sleeping in contact with them, but if they are physically mature, each must be in their own nightclothes.