In the comments, Wendy mentioned that her daughter is sure she doesn't have any siblings in China. That was one of the things we had to deal with recently.
We all know that the one-child policy is really a two-child policy in many parts of China. And we know that the mostly likely children to be abandoned are second daughters -- a family that has one daughter can try again for a boy, but if that second child is a daughter they have met the quota and can't try again for a boy. Unless, of course, that second daughter disappears . . . .
(BTW, Kay Johnson's book, Wanting a Daughter, Needing a Son, is great, in explaining the second daughter phenomenon and Chinese public opinion about abandonment and adoption. It isn't terribly well-written -- it reads like a string of articles in Population Control journals (which is what it is!), without any editing. So there is considerable redundancy. But the information is priceless, and well worth slogging through the poor editing. I hate saying anything at all bad about the book, because I hope ALL China adoptive parents will read it, but the truth is the truth!)
Anyway, when we started talking about why Zoe's birthparents weren't able to parent her, or any child, I started searching the internet for new books suitable for an older Zoe. (I swear I have every children's book about adoption, but most Zoe has kind of grown out of). I found a terrific one: At Home in this World, by Jean MacLeod. It has a great age-appropriate (age 7-11, I'd say) explanation of the one child policy and the social preference for boys. And then it says: "I might have been born a second daughter and my birthparents might have felt they needed a boy."
Zoe was reading the book, and when she came to this line, she asked what they meant, "second daughter." So I explained about the two-child-policy-if-the-first-is-a-girl, reiterating what we've already talked about the social preference for boys. I said, "The girl in the book is wondering if she might have a sister in China. Zoe said immediately, "I already have a sister -- Maya." I agreed, and then I said, "We don't know for sure, but a lot of girls who get adopted from China might have older birthsisters in China. So you might have an older birthsister in China."
Zoe SLAMMED that book shut and thrust it away from her, clearly rejecting the idea that there might be a sibling in China. She definitely wasn't able to deal with that idea.
We've talked more about it since then, and she's gone back to read the book all the way through. But the possibility of siblings in China is still bothering her, I think. Part of it is that feeling of rejection -- why would they keep that baby and not me. And part of it is that the list of what we don't know about her birthfamily keeps getting longer. I'm sure we'll be talking more and more about it.