Hi nontroppo,
I’ll post any updates/information on the LaTeX-natbib limitation to 26 identical ‘author-year’ references if/when I have learned something new. I welcome any thoughts or comments you or anyone else may have on the subject.
I don’t know if/when I might try to convert my natbib based references to biblatex as you suggested. Any thoughts or recommendations you may have to help me do so would be appreciated. StackExchange has been of some help, but the depth (or lack thereof) of my knowledge of LaTeX is affecting the transition.
I am still a neophyte on this new L&L forum, so I hope this note is properly posted, my apologies if it is not.
Thank you for all you help,
scrive