My step-brother is a US citizen but is working abroad in Europe for a European company. He would like to open an account (under my friends and family master account) but we're not sure how to fill in his address -- should we fill in his address in Europe, or his US address (with his mother -- but he obviously lives in Europe)? He understands he'll be responsible for US taxes on any profits-- we just want to avoid unnecessary paperwork and/or red tape if possible.