2,185. Who May a Doubtful Mamzer Marry?

Hilchos Issurei Biah 15:22

A doubtful mamzer may not marry a mamzeres, not even a doubtful mamzeres, because one of them might not be a mamzer and the other one is. A mamzer only under rabbinic law may marry a mamzeres only under rabbinic law. Similarly, whenever a person may not marry because of a doubt, two people who share this status may not marry one another.

Hilchos Issurei Biah 15:23

Pursuant to the preceding halacha, a shetuki, an asufi and a doubtful mamzer may not marry one another; if they did, they must separate with a get. The offspring of such a union are of doubtful status just like their parents. People of doubtful status may only marry converts (who are permitted to marry both born Jews and mamzerim). The status of their children in such cases follows the parent with the lesser status (as we will see in the next halacha).