Knowing the ethnicity and religious affiliation of your ancestors is very important, because it tells you where to look for their church vital records and which community to look into for contacting possible descendants.
I have attached the listings from the database of the Serbian Trade Association "The Merchant" sponsored children for the period 1889 -1943. The families and people from these places listed in these records were ethnic Serbs of Eastern Orthodox faith.
Serbian Genealogy Society SGS"Rodoslovlje"
http://www.rodoslovlje.com/en