I will be coming to Isca Sullo Ionio in November.

I can't help. You could contact the Comune and ask them for the last known address of your relative, you'll need to obviously give detail such as name and date of birth. If you give them enough ti.e they might help. If they give you a last known address then you could see if  the address is still there via Google and then when you visit. The other place for older records is the church for christenings and marriages. Good luck.