Hi Beth Ann:
The diaspora from the village of Potoczyska was large, considering especially that the village numbered about 2000 individuals in 1900.
I have reviewed and partially documented the two LDS microfilms of the metrical books of the village. It is apparent that the same names repeat, over and over, with multiple marriages among the families. It is not surprising that there would be multiple individuals with the same names.
I started my research by trying to document the links among the various Gulenchyn families in North America......and largely failed! I have not yet given up on this project, but it awaits retirement from full-time work.
For your interest, I have attached two pictures of the church in Potoczyska taken when we visited in 2007.
Your Szczerbaniuk (consistent spelling in Austrian records), Kozlo, and Sawicki ancestors would have worshipped there.