I don't know if we're missing anyone as yet, but I reckon @Ceta de Cloyes might as well get us moved forward.
You know what we might do, and I don't know what the canon on this is, but we might just hold on to the cube, so that we can introduce new characters as needed. Is it like, expended when it's used?
Canonically I know they didn't keep it at first but it was rediscovered later and that for it to work someone who already had morphing abilities had to be touching the cube along with those wishing to gain the power. I think it would make sense for them to keep the cube to protect it from falling into yeerk/controller hands though.