Ok, I am about to clear out some of my unused GF abilities to make room for some better ones, especially since a few are maxed out. I am wondering, the GF abilities SumMagic, and other abilities that add to the GF itself, do those add together and give a cumulative effect, or does just the highest ability take over. Wondering this because I am wanting to clear out Summagic 10% and 20% if the 30% is the only one that takes effect.

That's a good question, but I think that the highest ability takes over. But I also think that you need the others in order to keep the highest.

They are cumulative, and no, you don't need to keep one to retain another. You should have a sift through, and where GF's are allocated always to one particular character, and where abilities such as HP-J repeat themselves two or three times on one person, consider deleting those. They're easily learned again with goods from Timber if you mess it up anyhoo.

So it's imposible to have them all