[Ger-Poland-Volhynia] Saratov / Volga - German connections

[BirgitSteinke&GerhardAJabs]

Hello,

my grandfather Robert Jabs (1905-1946), my greatgrandmother Wilhelmine Schielke
Jabs Trautner (1870-1837) and two of the sisters of my grandfather - Olga Jabs
(Eddinger, 1900-1998) and Augustine Jabs (Kleister, 1902-1994) - had been deported
from Sierpc/RusPoland to Saratov/Volga during WW I (about 1914-1918). Olga Jabs
was confirmed in 1916 in the Lutheran Church in Saratov/Volga. -

How could I get more information about the church and the parish, e. g. confirmation
records? I have not been successful with church records at the FAMILY HISTORY
LIBRARY CATALOG of the LDS. Several books and maps are listed there, but none of
them seem to be for the deported Germans from RusPoland. 
I also would be interested to get more information about the address, where my
family had been living! Which archive could be asked?

Thanks a lot!

Greetings
Gerhard A. Jabs