Quote Originally Posted by Savannah
Yuffie -> Selphie -> Rikku
Tifa -> Rinoa -> Garnet -> Yuna
Zell -> Wakka
Barret -> Steiner -> Auron
RedXIII -> Quina -> Kimahri
If you insist on grouping them like this, i believe:

RedXIII -> Freya -> Kimahri
Vincent-> Amarant-> Auron

would make a better grouping in terms of both personality and roles