You may have a name change, or name anglicisation (from migration) as Caplan and Wolf are not particularly Suwalki type names. Wolf is a common first name.
You can try Litvak SIG or JRI Poland, but the best place to start is your ancestors' naturalization record, as the is the place most likely to give the name of the town or shtetl your ancestor came from, or sometimes you can get these from census records. Also any name change may be on these records.
All my ancestors came from the Suwalki Lomza or Kovno gubernias, and I used a combination of naturalisation records, the census, Litvak SIG, JRI Poland and the records for the former Suwalki Lomza Interest Group (now defunct) which were presented in their magazine Landsmen. I got all their birth places this way.
You do need to beware of name changes, which can happen multiple times, and also note that many reverted to their patronymic name on migration in preference to the name they were given by authorities in the old country. My great aunt Leah Servian (Serwianski from Sejny in Suwalki Gubernia) was buried as Leah Max in 1894 in North Wales, after her patronymic (Mordecai was her grandfather). Her widower Max Goldblat (whom she had married in Liverpool in 1887) remarried and changed his name in Britain to Morris Max and then Morris Marks.He emigrated to Chicago in 1905 with his 2nd wife Sarah Klein of Bradford, and changed his name to Aaron Marks.His descendants assumed his name had always been Marks, and so could not find him when they came to Britain to search for his family. They did not know about the name Goldblat (he came from Kovno).
The answer is that you need to think laterally.
Jill Whitehead, Surrey, UK