@devatha
the rule for the stimulus is that only those family members who have a SSN are eligible for the stimulus. So what should have occured is that Line 28 of your tax return reflected 2 family members with SSN LESS what was received for stimulus last March - May, 2021.
if you submitted your tax return with an ITIN for the Non-US child and the SSN was issued prior to April 17, 2022 (due date of the tax return) or Oct 15, 2022 (if there was an extension request filed), then YES, you can amend.
Also, this should make you eligible for the Child Tax Credit for the non-US child (assuming the child is under 18 years old as of 12/31/21 and you all lived in the US for at least 6 months of 2021).
it needs to be paper filed and that means it'll be a 9-12 month wait, but it should get taken care of.
