Ian,
Many thanks for your kind help with this. I was able to merge the two files (by hand - WinMerge showed too many changes). After the upgrade, it blew chunks, and I finally figured out that it was because I had a missing end comment. Fixed that and after a heart-stopping 30 seconds, it installed, and all looks good.
It gave a couple errors on some of the minor SQL upgrades, but did install all the way up to 4.8.4. Should I worry about the smaller errors? It seems to be working OK.
Thanks again for your help, and have a great long weekend!
Tom