My records concern the Lazar Koppstein who was born in Lackenbach, who died in Siofok, and who was the father of the following two sons who married two sisters:
1. Jozsef [born ~1838; married Henrietta ("Jetti") Singer; died 1883 in Siofok]
2. Karl [born circa 1849, married Paula Singer; died 1921 in Vienna)
The other details concerning this Lazar are unknown to me. The difference in spellings (Koppstein vs Kopstein) is possibly indicative of identity conflation.
Peter Koppstein, 2015