The detailed instructions for Brawl Bugs Patch say:
Only use the "Compatibility Edition" main file. Not necessary for Extended users that are installing Enhanced Blood Textures.
This is not ideal since it means that installing STEP Extended means you need to change STEP Core.
I think a better solution is to
1. Always install Brawl Bugs Patch
2. When installing STEP Extended, install Enhanced Blood Textures and hide the bsa file which contains contains jonwd7's brawl bug patch.
I think that solution would still work fine even if Brawl Bugs Patch is replaced by Modern Brawl Bug Fix.