Reeses is well aware that Mana went COMPLETELY INSANE after he, as Neah, died. It only adds to his extreme hatred of the world as it is now and his desire to destroy the Noah utterly and entirely, himself included.
There’s a good chance Allen’s mother was not his mother at all, but someone looking after his insane father, who Allen was too young to recognize as being insane. It's questionable whether or not Mana was his biological father at all.
After his death post-Reset, Mana became aware of his pre-Reset memories. He’s been haunting Allen for years, insane ghost that he is, and waiting for his brother, or Allen, or both. But he’s kept himself from being known by Allen, because well, Allen can’t handle being around ghosts because they kill his head in very unpleasant ways. (The only people aware of him are the Sleepwalking Allen, who Mana doesn’t hide from, and Allen himself by proxy of Sleeper. Allen’s still unaware of how messed up his father is/was.)
Allen doesn’t remember when he started calling himself Allen, or when he started thinking of himself as Allen, or even a time when he didn’t have the name Allen. This is possibly Neah’s fault. The least he could do was make the kid think he had a name.
His “family” over in England are the “Kamelot” family. They don’t know that the kid they got called to take care of was Allen, otherwise they would’ve taken in the kid immediately. It was initially the Earl that said not to take him in, because surely a child that had lost his parents would give way to despair and call him at some point anyway. Allen was too busy trying to survive to bother.
Instead of having new memories entirely, Neah made sure that all the Noah went into something of a coma of nonexistence after the Reset. They only became aware of the world again in 1984, and have no recollection of any of the canon exorcists.
The Order DOES exist, but the only one aware of it is Bookman, and possibly Lavi (and of course the Noah). But Bookman’s duties have been put on hold because, likewise, the records for the past hundred years have been completely wiped clean and no one fucking knows why.
Did we mention that REESES FUCKING HATES EVERYTHING? Because, yeah. He does.
Road, after the Reset, started searching the world for Neah, because she’s unaware of Allen’s existence and she knows that Neah will be reborn in the world SOMEWHERE and DAMN IT SHE WANTS NEAH. The Earl doesn’t mind this because he kind of wants Neah dead and wants him back at his side allll at the same time.
Bitches Noah have control of the ark. And England. England is the new Japan. Japan isn’t much better off, but has been left in a decent state because Wisely is a fan of modern manga. He’s especially fond of One Piece because it’s fucking weird.
Tyki is off hoboing it up somewhere, and trying to keep an eye on Road at the same time. He was heartbroken when he woke up to discover that his Hobo family had died. (He traced it back; (His Hobo family all died in a mine cave in, which, if his Noah has awakened, he probably could have saved them from.) Tyki never properly awakened, though the family is aware of him and Road still loves him. He avoids the Earl when he can.
Cyril is Cyril.
The Earl is pretty pleased but he’s not pleased about the supposed end of the world coming up, because hey, that means they die too. BUT LACK OF EXORCISTS MEDDLING this is nice.
Order only has a few members, and they’ve been actively trying to rid of world of the remaining Akuma while the Noah were kind of missing. They almost succeeded, too. But then the Earl woke up and realized that EVEN MORE PEOPLE ARE DYING THIS IS GREAT and now like ¼ of the world population are Akuma. He mostly just lets the other Noah mess with the remaining exorcists because lol, even if they never found The Heart, the Exorcists are no threat to them now.