My husband is also descended from John and Lena Koski.His grandfather, Stephen Dennis Koski, was a son of John and Lena.In the 1880 census John and Lena JasKoski are living in DuBois, Washington Co., IL.John is 26 and Lena is 25.Their son Thomas is 1 year old, so I agree that this is the right family. Grenowefa is 6 months and also living in the hh is Mary R. Maliska.Do you think Mary might be Lena's younger sister and Maliska might have been Lena's maiden name.
Grenowefa does not appear in the 1895 Kansas State Census, but their other children Thomas, Fred, Stephen, John, Mary, Kate, and the twins Anna and A (Anette or Nettie)are in the hh.In the 1900 Fed. census Lena reported that she was the mother of 12 children, 9 of whom were living.
The 1900 Fed Census shows John and Lena and all of the above children plus their youngest child Robert.The 1905 Kansas State Census shows the Koski hh in Atwood, Rawlins Co., KS with Fred Koski, age 21, John 19, Mary 18, Ann and Kate 14 (I think this should be Ann and Nettie 14) and Nettie 16 (I think this should be Kate 16).Lena died in 1902 and is buried in Mt.Calvary Cemetery near Atwood, KS. Her gravestone has the name "Kate" which must have been a nickname.
I may have marriage records for some of the children of John and Lena.Do you have any information about John Koski after the 1900 census?