I'm kinda in both of those moods right now, so this book is just memes, funny stuff, etc. Yes, the two fandoms have merged together in this, because I'm equally obsessed with both right now (for Keefe and Adrien/Cat Noir reasons). Yeah, they all know each other, I don't care. And yes, Marinette and Adrien know each other's superhero alter-egos, since it's gonna be tough if they don't.
KOTLC belongs to Shannon Messenger. Miraculous Ladybug belongs to Zagtoon/Disney (I think Disney's slowly buying Miraculous)