Alright, I have this file folder of stuff.
As far as I can tell, George Collins (founding member of the ABF) was going to write an article for the Fretted Instrument News on the Zither Banjo (I don't know if it was ever published as there is a draft of it with a rejection letter stapled to it).
So it seems that Collins started writing to Broomfield on the subject. This prompted Broomfield to sit down and type out excerpts from many (all?) of the letters Cammeyer wrote to him. Each excerpt includes the letter date.
Also in this file are Broomfield's letters to Collins as well as a single actual letter from Cammeyer to Broomfield (I suppose this was sent to Collins as proof of legitimacy to the excerpts). There is a very nice drawing of a zither banjo (I don't know who did this) and some other info including the page from the BMG about Broomfield getting Cammeyer's first zither banjo.
None of the info in the letters is groundbreaking, though they do serve as evidence to put this "Temlett invented the zither banjo" nonsense to rest. But all is very interesting.
So to my question... what to do with it? Technically, I believe all would still be under copyright, being unpublished letters. But I think this is important stuff. Should I go ahead and scan and post it and take the risk that some ancestor of Broomfield, Collins or Cammeyer's sister might complain?