Good to see that Nicolai didn't actually fall for something entirely made-up here, aside from details like the probable Karlchen confusion. No Völker mention in the digital part of the state archive (also, that name is really impractical as a search term), but I saw that Preuss in his Fritz-bio sums it up in a very no-nonsense way, saying about the poisoning stories that "[t]his is all made up. Glasow abused the governement seal [he says Regierungssiegel, not the King's, so I suspect he read the state archive letters, too] to issue some orders in the King's name, with the help of the Kaffetier Völker." So no mention of seduced Glasow, which means he isn't just following Nicolai I'd say.

The other thing about all this? I'm amused that "Kaffetier" is an official job description. (And probably one that aided the poisoning rumours.)