Thanks for your help.
Yes, I'm aware of the Zera public family trees and have provided information on Walter Proszogulowicz who married Therese Sadie Zera. They lived in Trenton NJ, Walter died in 1983 and Sadie around 1975. No children.
I had seen the ship's manifest and deciphered it as saying that Antonina's brother Yosef Laurinovicz was in the USA at that time (1913). Clearly missed the reference to the children's father being in the US at the time and will have to go back to the library to double-check (only have subscription to Ancestry.com for UK and Australia at present).