[Ger-Poland-Volhynia] Grenke and Fritz

[J GRENKE]

I have recordsfroom SGGEE MPD for Justine Fritz married to August Grenke from 
Lubsin, Radziejow, Kujawsko-Pomorskie, Poland

and St. Petersburg notes on Justine Friss and August Grenke in Volhynia.
Family notes and hear say Justine and August were from Russia.

My first question is at anytime could his area of Poland once been part of 
Germany. 

If not would their be reasons why they would say they were from Germany and not 
say Poland?

Can Fritz and Friss be the same name in another language?