Related for Yevamot 197:8

Rabbi Meir used to say: It is possible for a man and wife to raise 5 nations. How so? A man who (sic! reading Ehrfurt manuscript's מי against Vienna's גוי) has a male and female slave and they have 2 sons. One of [the sons] converts—behold one of them is a convert, one is a Gentile. Their master converts, he converts the slaves and they have a son—he is a mamzer. The female slave is freed and that slave has sex with her and they have a son—the child is a slave. They are both freed and have a son—the child is a freedman. It is possible for a man to sell to his father and pay his mother her ketubah. How so? A man who has a male and female slave and they have a son. He frees his female slave and marries her and writes his property to her son. He sells it to his father and pays his mother her ketubah.