Thank you to all the list members who responded to my query.
I didn't realise that the sz ending was the official hungarian way of writing it. (Which explains to me why the occurrences of that name in Hungary itself, seem to be always spelled that way). - My ones have it written both ways. Grosz and Gross .... (didn't think of Gros).
One member very kindly sent me the Stader pages for those names, so I have a bit to go on now,
Thanks again for all your help,
Ron :)
greetings from sunny Australia