Hello, Jim. I just returned from a visit to Iwonicz (my first trip to Poland). There are plenty of Kandefer surnames in Iwonicz; one (born 1924) even married one of my first cousins once removed.
I have not done any research on the Kandefer relatives, other than those found from my grandparents' siblings forward. If you have any interest in paying someone to go to the parish and search the records, I may be able to put you in contact with someone in Iwonicz. Otherwise, I do not believe those records are available anywhere outside of the parish, diocese, and Poland National Archives; they are not part of LDS microfilms, to the best I have been able to determine.
I am paying someone now to research the surnames of my two Iwonicz-born grandparents to the extent that my budget can afford this hobby.
I would be happy to answer any questions you might have about my overall impression of the Iwonicz area, as it is today.