Take a look at this example:
She might affect ignorance but don't be taken in because there's more to her than meets the eye.
Why to is used? The sentence clearly means that she has something of her personality you can't notice immediately. However it sounds a bit strange to me since in that context I would have used in or of, which I think give a better sense of "that hidden thing" owned by her personality. What tricks me is that, to my sense, the preposition to represents a one-way like concept, going from one point to another (e.g. "Give it to me", "I went to Rome", "Tell the truth to the police",...), while in that sentence nothing is moving "through to"; the preposition is kind of descriping a quality of the girl.
Is there a grammatical explanation? Are there other examples of this peculiar use of to?