I was just going over some of my info and remembered my grandfather's brother Andro Belobraydic married Catharina "Kata" Pintar. Her sister Klara Mara Pintar married Josip Nicholas Muic. They were both born in Knezgorica, Croatia, a small village east of Vukmanic. They also lived in Collinsville, Illinois.
See why I believe there is a relationship.