C.S.
I have the same issue with my daughter's grandmother, but mostly deal with it successfully even though she calls me by her grandmother's name when she's been with her for a while. Sometimes I'm even jealous because she doesn't treat my mother the same way. Secretly I think her father's mother is a silly goofball who identifies better with a child than she does with grownups. Bottom line, when she really needs you she knows you'll be the one who's there night and day, rain and shine. I always try to remind myself that I'm the adult, she's the child, I don't say anything negative about the other person, in time she'll understand that it's not always the "fun one" that's the most involved with her well-being.