The name Samuel mutating into Schiel is possible, depending on the
documentation. Samuel in Hebrew is Shmuel, and with a certain Yiddish accent
is pronounced Shmiel (or Shmeel). So if the documentation of Schiel is
either sloppy handwriting with a hidden m, something copied that may have
missed an m, then Schiel is possible.
But Schiel could also be >from Saul (Shaul in Hebrew, maybe pronounced Sheel
with a certain Yiddish accent).
I think that this is another demonstration of the principle that
corroborating evidence should always be sought, to either confirm or exclude
a person as a relative - one document often isn't enough. So if possible,
find more information about Schiel in Hamburg, like where he was from, or
whether his parents names match his expected parents names.
New York, N.Y.