Talk of Fakes (or Antiqued newer Basses) came up......

[Martin Sheridan]

Sometimes information gets shifted around in the old brain and doesn't come out right later when one wants to make the recollection.

I may have associated Guadagnini with Cremona for erroneous reasons.
A lot of people went through the shop of Nicolo Amati. There is one Stradivari violin from his early period that says "alumnus Nicolo Amati" but there is no other information that I know of that links him directly to the Amati shop. Since he lived in Cremona he may have simply walked to the shop for instruction, there would have been no need for him to have lived there. His early instruments bear a likeness to Nicolo's work, but someone pointed out that he was so talented that he might have just copied one.

The reason I mention this is that I believe there are some Guadagnini instruments that bear the inscription on their label as "alumnus Stradivari". That of course doesn't mean that he was Stradivari's pupil. It may only mean that he was trying to get a few more pesos for his work.
On the other hand a lot of people went through Stradivari's shop who might not have been recorded as having worked there. Some think that Guarneri del Gesu may have worked for Stradivari during the ten year period where we find no instruments made by him.
In the case of Guadagnini we know from Count Cozio de Salabue that he employed him to make instruments for him from the molds and designs of Stradivari that he purchased from Stradivari's son Paolo.

I wonder what Duane Rosengard has had to say about it? I understand that he has a new well researched book on Guadagnini.