Wendy, Here is the address format. This address is from the Slovenian on-line telephone directory.
6258 Prestranek, Slovenia
alternate format (I've used both successfully)
The second form is that used by my Slovenian relatives as their return address. I used the first form for my original inquires. Slovenia is a very small country, approximately 175 miles E/W and 75 miles N/S at the widest points. Even if both villages were at opposite points in the country it's conceivable to visit one in the morning and the other in late afternoon and spend several hours at each in one day. Give writing a try the worst they can do is ignore you.
Here's an alternative way to write. Go to:http://www.najdi.si/emails/
Put in the surname you're looking for in the box and click the red button. You'll get email addresses for those surnames in Slovenia. There are numerous listings for surnames Bole/Obreza/Zagar. My experience is that most will not reply but those that do will be fluent in English and even if not related may be able to assist you in small ways just to be friendly.