Please clarify -- do you mean you think that you recall reading that she thought she envisioned angels? As opposed to you thinking that actual angels of God would do such a thing?
I just read it again and I see that you are referring to your sister-in-law and what you think you recall her saying, and not to Ms Clancy in the OP. Apologies.
My sister in law heard voiced in her head. She said once, only once, as i recall, that they said they were angels. But they were teling her bad things. They were clearly not angels. They weren’t demons either, they were simply not real. She was insane in that time. postpartum psychosis is just that, it’s temporary psychosis, madness, insanity. She was behaving as she never had before and we were all worried she’d hurt herself. We didn’t worry about the kids, but we should have.