The Book Switch Theory

[asteckley]

1) Wilfrid Voynich said in his 1921 lecture to the College of Physicians in Philadelphia that he found the Marci letter "attached" to the front cover of the VMS.  Is there any other documented reference to the Marci Letter being colocated with (even if not actually attached to) the VMS from PRIOR to that 1921 lecture?. 

There are some 1915 and 1918 newspaper reports where the letter is called a 'flyleaf' and some of the names in the letter are quoted. I hesitate to associate this to a communications error or just bad journalism. Undoubtedly, there are many more newspaper reports that have not been found (online) yet, but they will tend to copy each other.

Why do you hesitate to associate this to a communications error or just bad journalism? My first inclination was to assume there was a young "Jimmy Olsen" type reporter who totally mangled his own notes that he perhaps gathered from a verbal interview of Wilfrid himself. But in any case, a "flyleaf" is simply not a "letter" -- it cannot be assumed to be some kind of poetic license on the part of the reporter.
The mention of some of the names found in the Marci letter only means that Wilfrid was aware of the Marci Letter (or at least the information within it) but not that it was colocated with the VMS when he acquired it. So none of this, unfortunately, provides any evidence of the Marci Letter being colocated with VMS.

2) Likewise, in that same lecture, Wilfrid Voynich described the signature of "Jacobus de Tepenecz" found on folio f1r. (There are variations of the spelling - I usually use "Tepenec".) Is there any other documented reference to the presence of this signature PRIOR to the 1921 lecture?

There is a photo in the Beinecke libary that was taken before the chemicals were applied, in which vague traces of parts of the signature can be seen. Rich should have this on his web site. 

But the problem here is that there is simply no date AFAIK for that photo. It was presumably taken prior to the chemical treatment that Wilfrid performed but that could have been very close to (i.e. just days before) the 1921 lecture or it could have been much earlier, closer to when Wilfrid first acquired the manuscript.  So that photo contributes little towards assessing any evolution of Wilfrid's thinking or behavior during the 9 years after he first acquired the VMS.

On 5 I would personally rank Wideman as quite possible, but Rauwolf and Mnisowsky (between Tepenec and Barschius) as unsupported by evidence.
Ownership after Kircher does not seem to be by any individual, and certainly Beckx should not be misunderstood as having been the owner at any time.

I had considered including Wideman, but didn't since Wideman generally hasn't been an oft quoted part of the "standard provenance story".   Perhaps it is worth including too though.

On 6, the link between the Marci and Barschius letters consist of several documents, including the Kircher letter in Moretus' notebook, Kinner's reference to Marci sending the book, and Marci's printed book referring to Barschius and his inheritance.

True, but all of those other documents only further confirm the fact that there was indeed some document that was being passed around (what Rich calls the "Baresch Document" and what Jorge calls "Book A" -- I prefer the former label as it is more descriptive.) They do not add any weight to the claim that the Baresh Document was in fact the VMS. By contrast, what you see in my diagram constitutes all the information that may actually unite the Baresch Document and the VMS.