it'll work itself out, but not immediately. the claim will be on your 2020 tax return!
The stimulus calculation is really based on your 2020 tax return to be filed next year.
What you are receiving now is considered an ESTIMATE using the data from 2018 and 2019 to figure out the payment.
When you file next year that will be considered the "settle up". if you didn't receive enough, you'll get it through a credit on your tax return, if you received too much, by law, you will not owe it back.
So children born is 2020 (or to be born later this year!) are also going to get the $500 for their parents!
