try the Stephen Morse site at:
www.stevemorse.org to search the Ellis Island database (EIDB). Check off Lithuanian, Polish, and Russian for nationality. Just use the first few letters of the surname (e.g., SUC, PEC) to start with.
The 1930 Census is the most current one available. Have you found their entries for 1930? How about any Social Security card appplications?
Best advice is to start with what you know and work backwards. Do you have their obituaries and know where they were buried?
Lots of documents out there if you know where to look.
Tom S.