I may have skimmed through the initial post too fast, but I'm not seeing what the point of this is. Is this just to ensure that games that say that they are compatible with BRP truly are? Or is this to just put a legal stranglehold on a game system convention? If it's the latter, then good luck, because I have a number of D% games and none would work 100% with each other. They don't even pretend they are compatible. Though they aren't exactly all that different, either.
My next favorite game system to BRP is Blood!. And that's entirely D100 system.
RPGNow.com - Postmortem Studios - Blood!
The company that made that game also made a conversion for Runequest called Bloodquest
RPGNow.com - Postmortem Studios - BloodQuest
The two systems aren't very compatible. Bloodquest is mainly to import rules from Blood! into Runequest and CoC, to turn them into slasher horror style games.