朋友

這是您需要的資料

http://www.uscis.gov/family/family-us-citizens/spouse/bringing-spouses-live-united-states-permanent-residents

這是如果他們如果結婚,稅務的問題

https://www.irs.gov/Individuals/International-Taxpayers/Frequently-Asked-Questions-About-International-Individual-Tax-Matters

 

一些細節

http://lawandborder.com/issues-for-u-s-citizens-expats-in-filing-the-form-i-130-immigrant-petition-for-alien-relative/

http://www.nolo.com/legal-encyclopedia/strategies-applying-marriage-based-visa-if-couple-lives-abroad.html