Any Wrzosek's?

My name is Robert Wrzosek and I am trying to find any family that I don't know of. All I can tell you is that my Grandfather, Eugene Wrzosek, was born in Warsaw around 1923, and came to America in the early 1950's after the war. He had a sister who was abt. 20 years older than him and my dad remembers him calling her Rumcza. (I've typed that name in and I've found NOTHING with that name.) His fathers name was Jan (we think). my grandfather didn't tell my dad anything so that is why I am trying to figure it out the "hard" way.

Thanks!