Input that can be saved to a file

beth david mark helen
?
helen ben amy markC
mavia sarah mindy
beth mindy
?
skunk
beth diane

Input (in blue) interspersed with output (in black)

Line of group member names separated by spaces.
beth david mark helen
Line of group member names separated by spaces.
?
Current listing of contacts.
beth: david mark helen 
david: beth mark helen 
mark: beth david helen 
helen: beth david mark 
Line of group member names separated by spaces.
helen ben amy markC
Line of group member names separated by spaces.
mavia sarah mindy
Line of group member names separated by spaces.
beth mindy
Line of group member names separated by spaces.
?
Current listing of contacts.
beth: david mark helen mindy 
david: beth mark helen 
mark: beth david helen 
helen: beth david mark ben amy markC 
ben: helen amy markC 
amy: helen ben markC 
markC: helen ben amy 
mavia: sarah mindy 
sarah: mavia mindy 
mindy: mavia sarah beth 
Line of group member names separated by spaces.
skunk
Line of group member names separated by spaces.
beth diane
Line of group member names separated by spaces.
control-D
No more input. Final listing of contacts.
beth: david mark helen mindy diane 
david: beth mark helen 
mark: beth david helen 
helen: beth david mark ben amy markC 
ben: helen amy markC 
amy: helen ben markC 
markC: helen ben amy 
mavia: sarah mindy 
sarah: mavia mindy 
mindy: mavia sarah beth 
skunk: 
diane: beth