There is probably an answer on google, but I can't quite get the search terms right.
Heres the context.
My great grandmother - Born 1909. On 1911 census, with family listed as adopted daughter. (Oddly, she never called herself adopted, always fostered.) Here she has her birth mother/fathers surname. Sometime between here and 1923, when her foster mother died (foster father had died a few years prior) her surname was changed to her foster/adoptive parents. Despite being placed with them from a very young age (at least 18 months old, if not earlier), she was always aware they were not her real parents.
Questions:
How loose/interchangeable were the terms fostered/adopted? (I've come across the term nurse child on earlier records, which I understand is more or less fostering.) Is there likely to be any official record of her surname change? Or even any adoption record?