The Doll People, book 1
Ann M. Martin et Laura Godwin2003

Annabelle Doll is 8 years old--and has been for over 100 years. Nothing much has changed in the dollhouse during that time, except for the fact that 45 years ago, Annabelle's Auntie Sarah disappeared from the dollhouse without a trace. After all this time, restless Annabelle is becoming more and more curious about her aunt's fate. And when she discovers Auntie Sarah's old diary, she becomes positively driven. Her cautious family tries to discourage her, but Annabelle won't be stopped, even though she risks Permanent Doll State, in which she could turn into a regular, nonliving doll. And when the "Real Pink Plastic" Funcraft family moves in next door, the Doll family's world is turned upside down--in more ways than one!