If your great-grandfather was born about 1860, and was the son of Jan and Marianna, then he was the brother of my great-grandfather, Antoni Sinicki (1862-1924). His daughter, Eugenia Sinicka (1896-1958) was my mother's mother. My mother is still living, at 94 years; we live in the United States.
Do you have a family tree? I would appreciate any information you can share with me! Also, if you can write in Polish, I can read and write in that language.
2020-03-10 Alexandra Weldon