Yevamot 85: How Pure Are Your Marriages?

R. Pappa and R. Hina arrived in Hintzvu, where R. Idi bar Avin lived. When they got there, they were asked: Can the daughters of kohanim who are eligible to marry kohanim marry those who have been disqualified from the priesthood? R. Pappa and R. Huna answer differently, with different inferences, and R. Idi bar Avin gives his own answer (where was he when the other rabbis first arrived?). [Who's Who: R. Idi bar Avin] Note the importance of knowing one's ancestors, to a degree that most don't nowadays. Also, is the ketubah part of the marriages that shouldn't be happening to begin with? And what about the secondary arayot that are prohibited by Divrei Sofrim? Does that cancel a ketubah?