Is Darl Real?

It's clear that Darl is a very weird character in As I Lay Dying. He sort of unnerves both people in his family and strangers, has almost omniscient knowledge at times, and has an extremely strange ending. I was sort of confused by many parts of Darl's story in the book, and as I was trying to understand it, I had an interesting idea: What if Darl doesn't actually exist? 

There's actually a few places in the book where it's implied that Darl isn't real. Addie's chapter, at the end, contains a section where she's adding up all of her children. At the very end, after subtracting both Jewel and the child that would have been Anse's if not for Jewel, she says she has given Anse three children that are not hers. There are actually four; Cash, Darl, Dewey Dell, and Vardaman. Darl not being real would explain this. At the very end of the book, Cash says that this world and this life weren't for Darl, and Anse completely omits him when telling Mrs. Bundren about the family. The clearest example, though, comes right after Addie's death, where Darl literally says that he does not exist. He says that Addie "was" and is not "is," so concludes if his mother is no longer "is," he no longer "is" either.

Darl not existing would actually not contradict the main story that much. He is sort of a non-essential character in terms of plot, as he doesn't make any major decisions that affect others and does virtually nothing physical that's important except for burning down the barn (which I'll get to later). His personality is also sort of non-existent, as he virtually never discusses himself, and the only thing others say about him is that he's weird and sort of freaks them out. He's alienated from pretty much everyone besides his family.

His interactions with his family are really the most supportive part of this theory. He knows things about everyone that no real person would be able to figure out, like Dewey Dell's pregnancy and Jewel's father. In addition, pretty much every single time he talks to someone, all he does is reflect their own inner doubts back at them, sometimes even harassing them. Darl's dialogue, in many cases, could easily be what the inner conscience of the person he's talking to is saying, reflecting their doubts back at them.

So, if Darl isn't a real person, what could he be? One possibility is that he's completely in the imagination of the Bundrens, and for each of them he is just a personification of their conscience. But this doesn't explain Darl's one main physical action in the book, burning down the barn. I personally think that Darl could be representing a spirit/angel sent by God to help the Bundrens on their journey. His talks with them represent him helping them with moral problems, and his occasional omniscience would make sense. This could also explain why Cora, who is extremely religious, is the only one who really likes Darl. The barn being burned as an act of God is also backed up by something Cash says. He thinks that it's possible the river flooding was a sign from God for them to stop, that they weren't supposed to get the coffin back. This would support a servant of God then burning the barn in an attempt to stop the journey.

(This theory is sort of crazy, and Darl probably does exist. But still, I thought it was quite interesting how much the story would still make sense if he didn't given how major a character he was).