dissolution money award (Oregon)

My husband owes his ex-wife a money award in their divorce. It's not for support, as she made way more at the time than he did. The problem is, is that she keeps moving, and it's like pulling teeth to get any mailing information out of her. First time, when she moved to a different part of the city, we got her new address when we got a copy of my husband's credit report. Second time, when she moved to a different state, it took us 6 months and a lot of fighting and legal threats on her end until she finally gave us a PO Box address (claiming she didn't want me to go out of my way to stalk her, when I can barely afford driving to a different *county*). Third time, two months ago, she moved to a different country altogether. We found out from a friend several weeks ago. She has yet to inform us herself.
The local courts couldn't give us much information as they never had children together, and she hasn't updated her information with the courts since the divorce.
So, our questions are:
1.) Who's responsibility is it to update information in this particular situation, and is there a specific time frame?
2.) Do the rules change when one party leaves the country?
3.) What are our options? We can barely afford to pay the judgment to begin with, now the US Postal Service wants to charge me almost $15 to mail a check to the country she lives in.

She has to update you or she does not get paid. You can send a regular check by regular mail for a dollar or two abroad.

If you have to pay more for certified etc, due to the court order, then ask her for bank account info and do it that way or set up ACH etc.

Send to the last address you have until she informs you otherwise.