Team A loses a routine rally; Team B wins the point and goes back to serve.  Prior to the beckon, Team B sends up a sub, #11 in for #12 with the expectation that #11 be the server.  The scoresheet reveals that #11 was in the starting lineup, and should be in the process of rotating RF to RB.  However, #11 never left through a legal substitution, so #12 shouldn’t even be on the court.  #11 would be the correct server if we moved forward.  Further investigation reveals that #11 left the court for the Libero, and #12 illegally replaced the Libero.  (The Assistant Scorekeeper said nothing at the time.)  After the illegal replacement, Team B scored 8 points during several rotations leading up to the discovery.  How should the officials correct this situation?