They may have entered at a port other than New York.
Many of the ships >from Libau made a stop at Halifax before reaching
Ellis Island; your people may have disembarked there.
Many people entered at other ports, including Philadelphia.
Do consider points of entry other than Ellis Island.
Researching RAISKY/REISKY/RYESKY, ARONOFF/ARONOV, SKOLNICK/SHKOLNIKOV
GERTZOG/GURTH (Yelizavetgrad, Ukraine),
ISRAELSON, ADLER, ARSHENOV (Yevpatoria).