Commentary for Kiddushin 127:9

It is unclear whether R. Yeshvav means to say that even if a man marries a woman who is prohibited by a positive commandment, (such as the prohibition of marrying an Egyptian or Edomite for the first three generation) the child is a mamzer, then our problem is solved. But if all he meant to say is that a widow married to a high priest is a mamzer, then it is still possible for the father to disqualify his daughter by marrying her to someone prohibited by a positive commandment. Such a marriage would be valid and yet she would be disqualified from the priesthood.