In Parshas Yisro, perek 18 and pasuk 5 & 6 ( I don’t have Hebrew font ), the Torah describes Moshe Rabeinu’s wife’s father as his father-in-law. In addition, pasuk 7 describes how Moshe went out to meet Yisro to honor him.
Since Yisro was not Jewish ( he is described in the first pasuk of the perek as the priest of Midian ), this would appear to support Think Big’s position that there obviously are occasions when a link can be maintained between a ger and their relatives