Well, technically, you are right. I have two. Tanya is my step-granddaughter who I have come to love dearly ever since she came into our family a couple years ago. I always wanted a granddaughter and she is just the sweetest thing. Couldn't have ended up with a better one if I had hand-picked her. :-)
It sounds like Tanya is equally lucky to have you. My mom's sister had two boys and always wanted a daughter (plus I was the only girl on their side of the family) so I was essentially blessed with "two mothers" and a doting grandmother :o)