BuddyPress.org

Why don’t you just add two additional profile fields (last name & first name) , make them required so they show up on registration and then write a custom function to tweak the sign up email?

btw, this is standard across a lot of social media sites. Look at Facebook – aside from the fact that they login with email instead of username, they also have display name, first and last….just like BP can have. Make FullName your Display name.