To the OP of this thread. Are you sure your mom filed as HOH after she married and your step dad moved in?
I will say, regardless of her tax filings, the income and assets of your step dad need to be included on your FAFSA form. That is required. Because they are married on the day you filed your FAFSA.
So…if you are doing a 2021-2022 FAFSA, you need to include both mom and dad incomes from 2019 on your FAFSA form and any assets as of the day of filing.
You won’t be able to use the IRS Data Retrieval Tool if mom and step dad don’t file a joint return…so they will need to order tax transcripts from 2019. If there is something not proper on those…believe me, the financial aid department will speak up.