Canon can be split into three categories, "Canon", "Non-Canon", and 'Anime Campaign".
Canon
Canon is the Epithet Erased Show and Novels, as well as any supplementary media that does not contradict it. If there is a contradiction in canon (ex: Meryl also being on dispatch in EP 5-7 Novelization contradicts the conversation in "Redwood Run" between Percy and Eros), we would find a solution to amend it whether it's ignoring one, acknowledging both whenever it appears, or finding a less than obvious to make both true.