This looks like a pretty good summary of the stimulus bill's effect on individuals:
https://www.nytimes.com/article/coro...gtype=Homepage
Xist (and other people that didn't file tax returns)
I sounds like you should get busy filing a tax return for your mother and brother.
IRS Free File -
https://freefile.intuit.com/
From the IRS:
Non-filers: Haven't filed a tax return for a previous year? Take steps now.
The IRS encourages anyone with a tax filing obligation who hasn't filed a tax return for 2018 or a previous year to act now. – Pending legislation includes certain potential credits and rebates for those who have filed a return for 2018 and/or 2019. Those without 2018 tax filings on record could potentially affect mailings of stimulus checks
https://www.irs.gov/newsroom/irs-ope...tions-continue