The LA Assignment Thread XII: the LA-bors of Heracles

[Inevitability]

Is there a rule that if a creature is fully inside an incorporeal one, they are affected by it incorporeal touch? Because I feel like there should be, but I'm not sure there is.

The issue is that creatures rarely fill any of their component spaces (except, like, gelatinous cubes). The rules allow corporeal creatures of any two sizes to share space in a variety of circumstances, which already implies that sharing space isn't physical overlap.

You can't reliably assume that a medium-sized ghost in the central space of a huge-sized giant is automatically touching, because there's enough space for the two of them not to touch. A minimum of effort (that is, an attack roll) remains necessary.