My great grandfather, Antoni Zelman, was born in Pinsk the 12th of February of 1902, in Molodelchitsy (Russia at the time, now Belarus). Son of Andrew Ivanov Zelman and Agrafena Vlasova. I managed to get the baptism record from the archives of Belarus:

I know they migrated to Argentina in 1931 as it appears in the immigrants archive of people that came by ship

I have some pages of the Polish family passport which they came with but it doesn't actually say Nationality: Polish
Here is a link with the pictures of the Passport.
Passport Pictures, Click Here
My grandfather, Michel Zelman, was born the 13th of January of 1929. I cannot find his birth records. I am not completely sure about the name of Michel’s mother, my great grandmother and Anton's wife, it may have been Weira Protazoviska, but I only have that information from my grandfather's Argentinean marriage records.
Being born in 1902 I know there could be army documents at Brest Archives,

List of town´s conscripts from 1921-1936
List of town conscript born in 1902
I sent an email enquiring about said archives.
And Census Archives

Census
Registration Card from 1919-1935
Census questionnaires from 1922-1931
I been asked to send a petition by post mail to get the military info but so far I haven't been able to do it.
I need to know what else could I find, I need the birth certificate of Michel, and a marriage certificate of Antoni, but I don't know how to get those.
How should I proceed?
Thank you!
