You're awesome, man. Replacing the folders with yours did the trick. Yea, you're right in that all the files are the same, and so the extra Sega levels should had worked just fine for me. However, after some sleuthing, I found that my sega.ini file I have is way different from yours. Thus, it seems that the only file that needed replacing was the sega.ini one. Indeed, I copied your folders to another location and put my original sega and sega levels back. I had the problems with the extra Sega levels again, but once I replaced just my sega.ini file with yours, then the 12 levels worked fine. Also, Superlemmini complains that the SegaR folder is missing if I don't have it inside the styles folder. Even if it's just inside the mods folder, it doesn't work, but once I have it inside the normal styles folder, then the Lemmings Reunion Sega levels load fine without crashing. No biggie, though.
Anyway, I attached my sega.ini file, and you'll see it's way different from yours. Thanks for your sega.ini file
I'll be using that since it fixed the 12 levels for me.
Now I have the itch to play through Lemmings Reunion again. I have your video to thank for that since I just recently opened up HurtMePlenty 25, because I somewhat vaguely remembered avoiding needing to use 2 bashers on the slope in Lemmini. Too bad I never saved any replays from before, so I can't say for sure if I'm remembering correctly. I likely didn't, since there's not enough time to do everything with just 1 lemming on Lemmini. So, I should have an LP of it in a few weeks
For NL, though. After that's done, I will turn to your SL conversion of the pack.
Also I'm remembering how excellent the pack is, hence my wanting to play through it again.