I am descended from the same Kos line.
I grew up in MN and know/knew the people you mention.
Louise Krob Weber just celebrated her 85th birthday earlier this month.
Your great-grandmother's parents were Joseph and Anna Kos. They lived in Mower County, MN and each summer a family reunion is still held there because that is where the majority of the clan lived and farmed until recent years. In the 1970s someone did a family tree for the descendents of Joseph and Anna Kos and distributed it at the reunion. I can probably get a copy of it from my dad, Ron Kos, who is the oldest son of Charles Kos -- your great-grandmother's brother.
James and Anna Kos had nine children that lived -- 11 all together. The ones who lived (siblings of your great grandmother) were: Anna (Funfar) of Myrtle, MN; Mamie (Sticha) of Clarissa, MN; Libby (don't know her married name) or where she lived, Lottie(Bednar) of Austin, MN; Josephine or "Josie" (Krob) of Austin, MN; James who lived around the Owatonna or Faribault, MN area; Frank who lived in southeastern MN; Charles who farmed near Myrtle, MN; and Edward of Austin, MN. This is not the correct birth order except I know Anna was the oldest and Charles and Edward were the youngest.
Your great-grandmother was called "Aunt Josie" when I was little and she made the world's best kolaches.