"For what it is worth, the NPS tour guides at Ellis Island today deny that
names were changed by federal officers."

Makes me nervous when federal people deny things and use terms like 
never/ever". Most of this was almost one hundred or over years ago.  There
is no one who can say for certain what any given individual said that long
ago.  As far as there being no official record or government form for/of it,
of course there isn't!

There are all sorts of just plain simple reasons that we will never figure
out because we weren't there.  My family name was changed from Menard to
Miner, could have been because it was Monday morning, an immigration
official thought my gggf, who either didn't speak English or spoke it with a
very heavy Quebecois accent said Miner or it could have been he wanted to
sound more "American" or perhaps because he was a miner or perhaps, etc.

Just some additional thoughts on the subject.
R. Miner