Barbara,
all of the 4 brothers are shown in the parish book of Pereszteg (with parents József Rokob and Erzsébet Grászli):
János Rokob: April 08 1870, died in 1915 Pereszteg
József Rokob: Jan 04 1879
Géza Ciprian Rokob: 14 Sept 1880
Gyula Rokob: 08 April 1884

The Rokob family lived in Pereszteg from the early 1700s, could be traced, with a lot of work of course.
Br
Laszlo