per Sue Monahan:
Their mother, Casmira, was sensitive about her name. It was "Old Country" and unfamiliar to Americans. So she decided that she would be "Kate." And she was adamant that it wasn't "Katherine." However "Katherine" does appear in censuses, on her death certificate, and probably elsewhere as well.

Catholic families had to have their children baptized with a saint's name. St. Casimir is the patron saint of Poland and Lithuania. "Casmira" is the feminine version of the name. There are numerous St. Katherines from other countries.

I was 12 when great-grandmother Kate died, so I knew her in her latter years. She had a hard life.

Yes, you may use me as a source. Her father's name is known to us, but not her mother's. The family story says that Casmira's mother and sister died in Germany, so her father scooped up his remaining child and left for America. He remarried, and had six children with his second wife . I haven't looked for any European records for this family.

Sue Monahan