Who are "the woman he knew" and "the woman he didn't know" in Lisel's answer for who killed Boy Staunton?

This takes place near the end of the book when Boy Staunton's son, David, asks the "brazen head" who killed his father. Liesl is the voice of the head and gives David this suitably cryptic answer. The statement is really up for speculation. Was the woman he knew Denyse? It was Dentse who drew Boy into politics and caused Boy so much stress. Is the woman he never knew Liesl? Did Liesl somehow facilitate Boy's death by convincing Eisengrim to tour Canada? I think Robertson Davies deliberately left these questions for interpretation. Remember, there are two follow up books to Fifth Business that relate to this question.