Conversation so far:
Whose idea was it to form R.E.M.?
Stipe and Buck met fellow University of Georgia students Mike Mills and Bill Berry, who had played music together since high school. The quartet agreed to collaborate on several songs.
Who were the original members of R.E.M.?
Michael Stipe, Peter Buck, Mike Mills and Bill Berry.

Question: Did they add anyone else?
Self-contained rewrite: Did R.E.M. add anyone else?