This does not answer the question of how was I ignoring the Succession of Witches. The Fated Children defeated the preceeding Succession of Witches as they travelled through Time Compression, aiding Ultimecia in to be given each of their power and preceeding that, it was with the help of Rinoa and Ellone, that she was able to possess all Sorceresses preceeding Adel. I'm not ignoring the Succession, the succession raises this possibility.
The point is that there clearly existed sorceress between Rinoa and Ultimecia. These are the sorceress we fight when heading to Ultimecia's time. The fact that they are killed by the party does NOT in any way change the fact that they exist on the line of time in FF8. They were not eliminated from existence, and so after the game ends, they will all rise to power succesively, and all be killed by Squall and co in turn and order.

So by saying Rinoa is the last in the succession before Ultimecia, you are ignoring all those sorceress we see, answering your question.

I'm saying... All things are possible.
I find it odd that you have spent pages debating when all you wanted to point out could be said in this tiny sentence. Because yes, "all things are possible", but this is not relevant! A rational debate cannot be based on this premise, because it means we must give a fair trial to theories such as "Squall is an evolved Shumi", "Irvine is Edea" or any other number of absurd notions.

The premise "all things are possible" works fine if you're writing a fanfic, but in a logical debate, it's worthless and cannot even be seriously considered for a second.