Just to finish.
When I made theories about FF8 I do the following:
1-I look into the dialogues.
2-I look into graphical details
3-I look into events
4-I assume that not every dialogue is thruth
5-I use the graphical details and the events as my final authority on deciding thruth.

Example:

Squall (in FH)-President Deling is dead.

In Deling´s residence we see his body lying on the floor.His body seems to have a lot of energy.And most important HIS EYE BLINKS.
Of course the people down there can´t see his body.And Squall believed in the general opinion.People only see Edea throwing the President high in the air.
So graphical details show that he is alive and the dialogue says he isn´t.
Of course I prefer to believe in the first.Dialogues are useful to reach thruth and interpret events but are never absolute thruths.
So the Sorceress uses regen on Deling (and some revive magic).We can also see a graphical detail about this.
So if there is a dialogue that shows that Ulti is not Julia I will only believe the graphical details that show she is.The dialogues then were lies.