After you file

No. I had 7 children under 17 in 2019 and 8 under 17 in 2020. 

(500x7)+2400=5900

600x9=5400

With the 2020 baby it should have been

(500x8)+2400=6400

600 x 10 =6000

Incidentally we did receive third stimulus for her. I have no idea why they included her for the third but excluded her for the first and second. She is eligible according to the IRS worksheet because she was a dependent in 2020.