Over time I learned another set of names for them: Isabel, Adelaide, Mary. It could have seemed strange to me that they would have multiple conflicting full names, but it never really registered. Even later, though, studying Chinese I encountered "dajie" (大姐) and "erjie" (二姐) as "oldest sister" and "second oldest sister". My grandmother, the youngest of three sisters growing up in China, had used these names for her sisters and, as hers was the last generation in my family to have any Chinese, the names fossilized and lost their positional interpretations. [1]

The extreme for this kind of preservation might be Kromanti, a ritual language of the Jamaican Maroons. At certain times, when an ancestor posesses a member of the community, they speak in a language appropriate for their era. The earliest ancestors, born in Africa, speak various lines composed of fixed phrases of a language which turns out to be a form of Akan, a West African language. (more)

While a few names is not nearly as interesting as a whole chunk of a language, it's neat to see this process in action in the speech of my own family.

[1] But why "Majie" (媽姐)? Asking my grandmother, she and her sisters made it up as a nickname, meaning something like mother-sister. Though apparently it also means something like "maidservant," and as a fluent Chinese speaker she would have known this, so I'm not sure what to make of it.