Naming convention question #names

Steven Usdansky

I'm curious as to the naming conventions that might be relevant as I try to determine if I might be related to a Warsaw-born Russian military officer and spy. His name is variously given as (using  Romanized forms) (1) "Stefan Lazarevich Uzdansky", (2) "Stefan Lazarevich Uzdansky (Tadeushevich)", and (3) "Stefan Lazarevich Uzdansky-Jelenski". No questions regarding #1,and it's the most common form used for his name. Regarding #2, where would (Tadeushevich) have come from? It's always given in parentheses in any document that uses it. Regarding #3, would Uzdansky have been one parent and Jelenski the other, and, if so, which would likely be Lazar's surname?

Steven Usdansky
USDANSKY (Узданский): Turec, Kapyl, Klyetsk, Nyasvizh, Slutsk, Grosovo
SINIENSKI: Karelichy, Lyubcha, Navahrudak
NAMENWIRTH: Bobowa, Rzepiennik
SIGLER: "Minsk"


I have found information about Stefan Uzdansky in Russian and the explanation is that his father had two names Lazar and Tadeush. 

So Tadeushevich is Stefan's second patronymic.

Lara Tsinman