No. The stimulus money will not be combined with your income tax refund. It will be a separate deposit or check.
How do we know for sure it cant be combined if it's going to the same tax account
The federal tax refund and the stimulus payment are from totally separate US Treasury accounts. So they must be separate.
See this IRS website for a non-filer portal and when stimulus payments will be begin - https://www.irs.gov/newsroom/treasury-irs-launch-new-tool-to-help-non-filers-register-for-economic-i...