Let me tell you, I was unprepared. It was a whole make-up bag with two packages of unused needs, about five used needles, a spoon, a mirror and a lot of tin foil. Oh, and matches. The spoon was very much not clean. My mother absolutely freaked. Then my brother is trying to work out what it indicates with knowledge that it's a good 20-30 years out of date. Fun times.
It's kind of like when you stopped believing in Santa Claus, but pretended to a little longer for your parents' sake.
Having given it a lot of thought over the day, I think what I personally can do is talk to her about what we are pretty sure is happening -- her mother telling her not to tell anyone about what happens when she visits. I think a conversation about how adults shouldn't tell kids to keep secrets is in order. I don't have to get specific. Just plant the seed that she shouldn't have to keep a secret and if she wants to tell me, her father, my brother, my mother something, then she should.