Sorry, but there is no answer to your question. This has been a issue for years and the IRS has not issued any guidance for this. Some just enter 0 (because the parents US income is zero) and print the tax return and enter FOREIGN in place of the SSN.
I am not recommending that and do not know how the IRS will handle it since there is the other option now that does not need the parents income.
**Disclaimer: This post is for discussion purposes only and is NOT tax advice. The author takes no responsibility for the accuracy of any information in this post.**
