Buzz Aldrin, the astronaut, was legally Edwin Aldrin up until the 2010s or so, when he was in his 80s. People had been calling him Buzz for decades, so I guess he figured why not.

Unrelated fact about Aldrin: his mother's maiden name was Moon. Bit of nominative determinism by proxy there.

My mother's situation is complicated by being a dual citizen – she'd have to update all her paperwork with the governments of two separate countries.

I am also a dual citizen, so would have the same issue – except unlike my mother, I can't think of any plausible reason why I might want to change my legal name.