I wonder, if it is any interest to you:
My mother-in-law's father was Izsak-Yitchok Yaakov Friedmann --a Kohen- son of Dayan, Harav Zvi HaKohen Friedmann from Beregszasz? Kezmarok?
Izsak,-- Yitchok Yaakov Friedmann was a 'Sochet' in OZD-Hungary--before the War--His wife was Sarah Felberbaum--I am not aware--it might be that Sarah had a secular name as well.
OZD is near Miskolc.
I am not aware that they lived in Wien or not, or if they had a restaurant or not.
On a different note: I also like to mention that to my knowledge, there was a Nadudvar ? or Nadudvari ? in Hungary as well.
Best wishes to you all and wishing you success in your research.