Kate and Marie Mertl

I have run into a brick wall in trying to find where my grandmother (Marie) and ggrandmother (Katerina, “Kath”) came from, and also who my ggrandfather was. All I have is a last name but do not know if Marie was Kath’s real daughter or was Kath raising her because a family member died? Was she born out of wedlock and was Kath’s surname of Mertl her maiden name or married name? I do know they were Bohemian as that is the language they spoke and passed on to their children as my mother and aunts and uncles (now deceased) all spoke Bohemian. Marie was born July 29, 1878 and came to the U.S. in 1882 at the age of 4 with Kath who was born in 1854 and died in 1912 in Minnesota. Kath was married to Gottfried Hempel after she came to the U.S. Marie died July 6, 1938 and she had married Vaclav “James” Smetana. I’m hoping someone in CGSI recognizes these names. Thank you for reading my query.