How many Black Knights (Black Wings Generals) are there really?

Somewhat offopic: Has Alcaster been given any new storyline in the Mercedes or Demon Slayer quests? He was arguably the most important person of rebuilding Ossyria after Black Magician's defeat (built Magatia, made Orbis float, sealed Zakum, etc.), would be weird if they neglected him now. The Magatia storyline clearly hinted that he stole his alchemy powers from Black Magician's studies, wouldn't be surprised if he had secretly been an old follower of him or something.