Your parents don't have to file a US Tax return, because they have no tax liability
to the US. IF they were to file a form, they would confuse the system.
Here's some ideas:
Contact your parents and ask them how much money they earn in a year. Ask for documentation. If it is not in American dollars then convert it to American dollars. Ask them how much they pay in taxes for the year, convert it to to American dollars. Ask how much they have in assets
, savings, every question thats on the fafsa... convert it to american dollars.
Be sure to put your address down on the fafsa and not theirs, be sure you include yourself in the household size even if you don't live with them, be sure you realize you will need their income
information until you are married, have kids, turn 24 or earn a bachelors degree. No way around it... you have to have your folks info on the fafsa. No matter where they live.
I would work on this directly with your school's financial aid office. Chances are someone there has worked on a case like this, and will know exactly what to do.