I stumbled upon this site quite by accident, when searching for my father, Edward Korncavage (Korney). His family was from Duryea, Pa. I don't recall a Stella. There definitely was an Eva, who died in the 1980's or 1990's, in Buffalo, NY. Avoca is the next town over from Duryea. Both my parents graduated from Duryea HS. My father was a WWII vet as well as many of his brothers; Edward was on the USS Bennion, a Navy Destroyer. I just returned from Duryea a couple days ago; the cemetary on Church Street is where much of the Korncavage family is buried, however the original name on the gravestone is KORONKIEWIECZ or something similar. I know this for a fact, as the "Korncavage" homestead is right across the street from the cemetary; the stone marks my grandparents, and I believe at least 1 or 2 uncles.
I don't know if there were any other Korncavage families in Duryea or Avoca at that time, or if there are any Korncavage families that ARE NOT related; I would also tend to assume that all the Korncavage families in that area are related. I remember the area is very "close-knit" as I was in the VFW post in Duryea since I was a baby, and everyone new each other; through much of my life, I've spent time in Duryea with relatives and have been in & out of that same VFW Post, only allowed in because of my name or who I was related to, so I think the family name is recognized as just one family in that area, albeit many brothers. My mother is still alive out here, but for a timeline to place the generation, my parents were born in the 20's, and my father was the youngest of all the brothers. He died in the late 1980's when he was in his mid 60's.
If this is the same family, much of it has moved to the Buffalo, NY area. My cousin remains on Church St in Duryea. I also have uncles in Johnson City (Binghamton NY area) and NJ, but for the most part, 4 of the brothers headed to Buffalo in the late 40's-50's, and the family name has again been shortened or changed.
Sorry all this is a little late for a class project, but maybe it will help someone else. Maybe Koronkiewiecz or however it's spelled is why you couldn't go back any further in the family tree.