That is a very interesting reference to Helen and Monobazus as "children of Ptolemy". We have already concluded here that Julius Caesar and Herod the Great were both of the Ptolemaic line. This has been a subject of intense study over the past year or so. For the salient posts, see:
We have also concluded that Cleopatra Selene (a.k.a. Muses) became the wife of Herod the Great (a.k.a. Juba II and Phraates IV). Her Herodian names were Mariamne II and Cleopatra of Jerusalem. By Herod (or some other royal male), she became the mother of Herod Philip I ("Zechariah") and Herod Phillip II ("John the Baptist").
The fate of Alexander Helios and Ptolemy Philadelphus has until now been a mystery. However, I would like to propose the following for everyone's consideration. After the death of their father Mark Antony, might not these princes have been adopted by Herod the Great and his wife Mariamne I, and as their sons called Alexander and Aristobulus? Herod was, it seems, too easily persuaded of their desire to overthrow him. He ultimately received approval from Augustus to have them executed.
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