I just thought of something, if you're fused, your summons should go away, and be replaced with one new drive summon. Valor's drive summon should be Ifrit, and Wisdom's drive summon should be Shiva.
Also, now that they're starting to get into talking about Twilight in KH2, they need to start having some light and dark looking summons. You know who that means. The ultimate dark summon! The one, the only, ANIMA! Tell me that wouldn't be cool!