Hardly butting in. You deserve all the credit for recognizing and sharing the importance of Cleopatra Selene within the ancient royal court network.
I doubt very much if Ralph Ellis reads anything on this web site. He runs with much of the same material, but in his own direction.
Possibly it is not necessary to propose a second unattested daughter of Cleopatra VII. Cleopatra Selene is a good fit for the "slave girl" presented to Phraates IV/Herod. It is less certain that Herod was inter-fertile with Cleopatra Selene, especially since she emerges as half-sister or perhaps even his full-sister. In other words, was Herod Philip the son of Herod the Great, or was he sired on Herod's behalf, and if so, by which other prince/king, such as "Costabar the Idumean".
If there was an unattested royal princess, she would likely correspond to Herod's sister Salome. Yet, if Salome was the full-sister of Herod, then probably both she and Herod were sons of a different (slightly older) mistress of Antony. If Salome was only a half-sister of Herod, then we should suspect that she was one and the same as Cleopatra Selene. As Herod's sister this princess was referred to as Salome. As Herod's wife, she was instead called Cleopatra of Jerusalem and Mariamne II.
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