We've always told BabyGirl that adoption is one of those things in life that's both happy and sad.
While we're happy that she's in our everyday family, we're sad that she's not in Mitzie or Raoul's everyday family; we're happy that she has us as her everyday parents, we're sad for her that she doesn't get them as her everyday parents; we're happy for us that they asked us, we're sad that they were in a position in which they felt they had no choice but to ask.
We always try to make it ok for her to have conflicting feelings about our adoption, that both feelings are true and honest, even if it's confusing to hold multiple conflicting emotions at the same time. Life is like that: conflicting, confusing, and legitimate.
Paragraphein expressed this dichotomy eloquently. Go check it out. Read it slowly and thoughtfully. It's worth your time.