An In-Universe Explanation for How Nightmarionne Became Canon

[Amazingspore1026]

I'll say this once, I do not think that Golden Freddy is possessed by the crying child. TOYSNHK is Golden Freddy and Golden Freddy was possessed by a victim of William Afton.
But Golden Freddy and the crying child could have, theoretically, gotten close during their time as spirits haunting Freddy Fazbear's Pizza.
We know that TOYSNHK can project images into William Afton's mind, that is what makes ultimate custom night possible, to begin with.
So there is a heap of evidence that CC is the FNAF4 player; steam summary, FNAF4 minigames parallel FNAF4 gameplay, character dialogue, and the fact that Fredbear references FNAF4 in his UCN dialogue.
And if CC died he and Golden Freddy were in the same restaurant together, then that means that they could possibly communicate, with, CC can do it for TOYSNHK albeit with less malicious intent, right?
This accounts for every animatronic I believe, TOYSNHK has seen himself or gotten info from communicating with another spirit.
He could have gotten the SL animatronics from the blueprints Henry found or communicated with Molten Freddy or Scrap Baby, we know he was somewhere in FFPS at least, so he would know all about those ones. He also would have to have been in Fazbear's Fright at some point to have knowledge of Springtrap and the phantoms.
And CC, CC must have related his nightmarish experiences with GF at some point.
it's nice in a way, knowing that poor little kid didn't have to deal with the trauma of those nightmares he dreamt up all by himself.
So TOYSNHK took inspiration and decided to sic CC's nightmares on William Afton later on.
So what about the non-canon ones? Yes, the non-canon ones are, well, non-canon-to FNAF4.
But this is TOYSNHK's prison, and TOYSNHK says, goes.
So TOYSNHK drew inspiration and created a tormentor out of his imagination, inspired by BV's nightmares. So Nightmarionne is canon in UCN beyond, but not in FNAF4. So that means that while most of these Nightmares are a product of BV's mind, Cassidy made Nightmare Mangle, Jack-O-Chica, and Nightmarionne canon.
Jack-O-Bonnie does not appear in Ultimate Custom Night, so it's likely Afton, during his escape and his subtle attempts to revive Fazbear Entertainment came up with the character and was able to recreate what was inflicted on him in Ultimate Custom Night. That's why I think the nightmares appear in Help Wanted: Cassidy got them from the Crying Child, (and made up some more besides, which included Nightmarionne) and William got them from his time with Cassidy (and still more besides)
For example, Yoda is a canon star wars character, but he does not canonically appear in A New Hope, so wasn't recognized as canon until The Empire Strikes Back. Nightmarionne doesn't canonically appear in FNAF4, but canonically appears in Ultimate Custom Night...as well as non-canonically appearing in FNAF4.