Oda said in SBS 59
D: About the Whitebeard Pirates, if there are pirates from the "Whitebeard ally groups", is there a possibility of one of them becoming a commander of the real Whitebeard Pirates itself? Or are the commanders all from the real Whitebeard Pirates from the beginning? P.N. amanuts
O: Ok, I'll explain a little about the Whitebeard Pirates. First, captain Whitebeard and the 16 commanders. All 16 commanders, despite numbers and ages have the same rank. All the same. Whitebeard Pirates are just split in 16 groups and the division number does not indicate strength.