Bram says he doesn't want Miles to go to the island as he is "not ready". Bram says Miles needs to go with them so he can learn what makes him special and learn more about his father. This seems to imply that Bram et al are DI.
A possibility. It might still be possible that Bram worked with Mrs. Hawkings who helped them get to the island and maybe she's part of the DI, too. Maybe she knew that if all six of them were on the plane she could get her people to the island, also.