What was XXX's child's name?
Cleopatra Thea
Demetrius set himself up as co-ruler with the young boy Antiochus VI, but may have killed him in 142 BC. In 139 BC Demetrius II was captured fighting against the Parthians and was held prisoner by them until 129 BC. After Demetrius was captured, his younger brother, Antiochus VII Sidetes, who was raised in the city of Side in Pamphylia, came to Syria and took the throne, marrying Cleopatra Thea in 138 BC. Cleopatra Thea bore him at least one son, Antiochus IX Cyzicenus.
Antiochus IX Cyzicenus