Hello Robert. I called archive today and they told me that they have a lot of JNA records. To be able to help they need more precise information. So, that lady should write as much data as possible (including her contact address/number) and send it BY FAX to this number: +385 1 4829 000.
That’s the fax number of Hrvatski drzavni arhiv, Marulicev trg 21, HR-10000 Zagreb, Croatia. If they find anything regarding her search, they’ll contact her.