Thank you, Charles Kenyon. (with, according to your imbedded comment, additional kudos to Timothy Rylatt)
Apparently all that was missing from my code was:
Thanks for the links. The "Situation 1" did not work, but Situation 3 did. And after stepping through the Situation 3 code, found that it ultimately resolved to the code I originally posted the exception of the statement you attribute to Rylatt.

Given that I insert the same building block item multiple times in my application, I'm not sure whether to use Rylatt's statement on each insertion or just the first one. But experimentation will solve that issue.

Again thank you so much for your patience and suggestions.