 I heartily agree and would be happy to assist you, THD3 (although I know that you have already written a your doctorate on Kappell so you probably know a lot more than I do on the subject!). I've a reasonable collection of primary and secondary sources (and, sadly, I have had some input to the circumstances of his death on Wikipedia as you will see from the link to BCPA Flight 304). BTW, the information you added about Kapell's parents I think originates from publicity in the 1940s/50s (for example see page 105 of Tim Page's book relating to the South American tour in 1948 just after his marriage to Anna Lou) and the omission of his Jewish background is probably a reflection of prevailing attitudes at that time.   