They should have stopped after 2 I agree completely with this!!
3 is a money making parody of the story and didnt need to have been made.
Another GF story should stand alone on it's own merits, maybe using the same family name and/or credentials but other than that be totally individual of the GF and the GF2 (if this make sense!!) IE not a GF 4/5/6 blah blah blah
