Sorry, should have include what few dates I knew. Anton had 5 sisters, two of them had birthdates of 1880 and 1874. Unfortunately, I do not know whether he was one of the oldest or the youngest, however, the estimated dates of birth would not seem to fit what I know about his family. He did come from Skala, Galicia, Ukraine. The surname also was spelled Prokopowicz, Prokopowich, and Prokopovich, depending on where you look.
Thanks for your help.