[Ger-Poland-Volhynia] surname variations

[Ohgrmtns at aol.com]

I have come across various spelling of (P)Feifert from various sources. How  
am I to know which ones are true variations and which are just missed spelling 
 on the part of the clergy or clerk that entered the information? Where else 
can  I go to determine this?
Thanks.
 
Kristen

Researching : (P)FEIFERT, STIEBNER, NEUBERT,  KOCHAN
Searching: Nedbajewka, Rohrbach(Berjozowka), Gruental, Kutuzowka,  Lublin