I like to think of her real power as being invisibility because this scene does not involve an instant and un-kid-friendly end by way of half a body here and half a body there. The rest of her body is clearly here, just unseen. I think she’s sorta getting her mental wires crossed when she triggers the spell so she vanishes in more ways than one, resulting in part of her seeming not to be there.
Baby Ribbon: Can’t! Not all here!
Baby Tiddley-Winks: Checkers all there!
Baby Ribbon: I’m not all here!