Ok i know I am new(just got net at home) but been FFF since 8 finished all but 2 3 5 6, but upto finale, I know I will get the same as the eada=terra thread but here we go
First of I think all connecting games are 1000-2000yrs appart

2-4-7
Highwinds, nuff said
1-3-5
All ready said that all odd NES/SNES are game play, so not mush connections except Warrior classes
6-8
Esper and GF similar System, GFs are spiritual Espers, EADA NOT TERRA

1-9
this is the goody for theorists, since 1 has the 8 time loop, its brocken at the end, 9 is the true way through the story+Sarah, BMAge WMage & Thief, my guess RMAGE becomes DRAGOON

unfotunatly I cant connect 10, except to 8, but thats character design

Delete other comp stuffed up

Firstly, welcome to the Forums. Hope you enjoy yourself while here.

Anyway, on the topic of your thread, for references between the various games in the FF series, you could do no worse than check out FF Compendium at http://www.ffcompendium.com/h/incross.shtml

There you will find listed pretty much every known crossover between all FF games, although much still lies buried.