Kupiskis sounds promising. How would we prove it? If I could just find the passenger lists and any/all of them, there should be a town on there...or more naturalization papers.
Most promising would be Sadie. Her husband Lasar Polonsky aka Louis Post was naturalized in 1914. I found the index record (Naturalization 12 May 1914, Louis Polonsky, 346 East 173rd St., Bronx, Vol 143, Pg 52; supreme court) but can't find the Declaration or Petition. According to the 1925 census Sadie was a citizen through her husbands papers.