Searching for information regarding these surnames from the Pidhajtsi area.
G-G-Grandfather Danylo Koszlak (Koslak/Koshlyak/Kosslak/Кошляк) immigrated to Canada in 1912. I've found his passenger manifest. He married wife Anna Bruchanska/Бручанський (but family remember her surname as "Benzik") in Brokenhead, Manitoba in 1914. Anna is mysterious, her birthdate always seems to change (1891-1895) and I cannot find a passenger manifest for her anywhere... closest was an "Anna Bruchnalski" (which I guess isn't too far-fetched...)
Danylo's parents remained in Ukraine - Prokop Koszlak and Krystina Fink/Фінк. Anna's parents are listed on her marriage to Danylo as Dmytro Bruchanski and Nastia Rozdobudko/Роздобудько, who also remained in Ukraine.

Looking into how to pursue:
a)research on older generation in Ukraine (could be difficult since my father was adopted and this is his biological family)
b)Anna's passenger manifest
c)Finding others with these surnames or researching other surnames in the Pidhajtsi area.