how do i gain gfs levels without gaining to many levels for my characters (is it possible)

<font color=red face="comic sans ms">No, you can't do that, as your GF's get the exp that the charcater they are junctioned to gets. Therefore if you don't get any exp from a battle, then the GF's don't either. However, if you don't want to gain levels, you can do a 'rotation system' with your party and GF's, swapping them every now and then to stop each character gaining too many levels, although this would be boring and still wouldn't be very effective.

If you want to level up any particular GF, junction it singly to a character. If more than one GF is junctioned to a character, they 'share' the exp between them. For example, in a battle that gives 500exp, with one GF junctioned, that will gain 500exp. With 2 GF's junctioned, they will get 250exp each. SO if you want any particular GF to level up, junction it exclusively to one character. So you can have 3 GF's junctioned at once, one for each character. Or you may choose to junction them all at once, it's your choice.

Just so you know, most GF's need 500exp to level up. Siren, Carbuncle and Cerberus only need 400exp, and Eden needs 1000exp.

But yeah, you can't level up your GF's without levelling up your charcaters. :\

Well early in the game you can put Shiva Ifrit and Quezacotl on Seifer and have him fight alone til they reach lvl 100. But later in the game the best choice is Cactuars which give 20 AP and barely any exp and fast to kill.