It’s not a silly question. Each “general” brush kit I publish replaces totally my previous one, for my own usage. But sometimes, I need to remove brush that I personally don’t use much anymore, but are still totally valid. I also might “butcher” the behavior of some brush in the previous version to fit my new usage.
I usually do all my possible so the new version of brushes are named to never collide with the previous version (using deevad YYYY.MM in the brush name, with the year and month of the release). So, it’s possible to keep all the brushkit installed without conflict.
It might bloat your “All” list of brushes, but it’s not really a problem if you create a tag for your favorites brush presets and only go back to the “All” view to make your selection/tests.