"Philip II (Latin: Marcus Julius Severus Philippus; 237–249), also known as Philip the Younger, was the son and heir of the Roman Emperor Philip the Arab ...
by his wife Marcia Otacilia Severa. According to numismatic evidence, he had a sister called Julia Severa or Severina, whom the extant literary sources do not mention, and a brother, Quintus Philippus Severus.[citation needed]
When his father became emperor in 244, the younger Philip was appointed Caesar. In 247 he became consul, and was later elevated by his father to the rank of Augustus and co-ruler.Their reign took place during the thousandth anniversary of the founding of Rome, and great games and spectacles were planned for the celebration." - (en.wikipedia.org 21.06.2020)