BuddyPress.org

Leave default theme where it is and before you upgrade BP in the future make a copy of the BP-default folder and then use your back up to overwrite the default files.

I’m having a similar problem where i have 20 child themes and only 4 php files are different. So I’d have to update 80 files each time I adjust something. Easier to just deal with keeping track of the default BP theme folder.

what would really solve this is the ability to have grand children themes.