I suggest you send a mail to Dr Alois Ruhri, head archivist the Catholic church's diocese office in Graz at:email@example.com
giving them as many details as you can regarding names, dates and places. However the generally do charge 25 Euro for their services.
Another place for the same enquiry is:firstname.lastname@example.org
where hobby genealogists are more than willing to help and usually come up trumps.