SSA sent a underpayment refund to my deceased aunt which s/b reported as income to her estate. The SSA1099 is in her SSN (vs EIN) and SSA won't change it Is this a prob?

No, this will not be a problem.  You will report the income on the estate's tax return.  

Thanks Leonard--will the IRS systems auto cross reference my deceased aunt's SSN to her EIN?   Her final 1040 tax return was submitted for the 2018 tax year; 2019 will be her first and final 1041.   Can you tell me what line I would report SSA-1099 income on form 1041?  Do I need to attach any explanatory notes or forms to the 1041 to clarify why my dead aunt has social security benefits after her death?  She had no parents, spouse, or children so that's why the estate ended up with the underpayment check, but this seems to be a very rare scenario as I can't find a single reference to this after spending hours and hours scouring the web.   TY