So I was just sifting through here once again and noticed your post. I lived in between Riga and Latgalea for almost 3 years, my wife is from Balvi and our son was born in Riga. Prieks iepazites
I was stationed at the Embassy in Riga.. good times.
Anyways, in regards to security clearances, when I held my TS/SCI your investigator will most likely contact your closest relatives and maybe a few friends. If your parents or siblings live in the U.S. he MAY travel depending on how far it is from his office. I have never heard of OPM or a contractor flying overseas to meet with anyone, much less if they are not immediate family. I wouldn't sweat it, if you've never held a clearance before you might get scrutinized but just make sure your 86 lines up with every other piece of paperwork and you'll be good.