Charles (Aron Zadok) Engelman (1845-1895) and Mindel Kucherovsky (1850-1918) of Bialystok, Poland, had 1 daughter (Freda) and 5 sons (Harry, Samuel, Max and Abraham) who immigrated to the USA.  Most settled din Pennsylvania. 

I was told that Charles and Mindel had 1 more son, Yosef Engelman, who remained in Bialystok.  He may have married Fajga (Feiga) Vegmeister (1885-1942?). They may have had several children.  Yad Vashem testimony (at https://yvng.yadvashem.org/nameDetails.html?language=en&itemId=300712&ind=1) may say she and her children died in the Shoah ~1942.

I'm trying to find out whether Yosel Engelman IS, in fact, another son of Charles (Aron Zadok) Engelman of Bialystok.  Does anyone have any documentation about the father/son relationship?  Where can I find this type of documentation/information online?  At the JewishGen databases, I see a Yosef Engelman from Bialystok, but I do not see any records to connect Yosef and Charles (Aron Zadok) as son and father.

Thank you very much.