If you mailed in a form 1040 AFTER filing a stimulus registration return then it may or may not be accepted for processing as an amended return ... there have been no information released by the IRS on this subject.
The proper way to file was to mail in an amended return form 1040X which under normal times takes as long as 4 months to process however since the IRS didn't open any mail for 10 weeks you can add another 2-3 months to the process meaning Thanksgiving at best.
There may be no way to track these returns thru the system since they are not original returns or amended returns so the IRS tools may be useless. All anyone can do is wait until the IRS has time to sort all of this out.
