So for each round you got it for 8 children. The 19 was too old for both checks. So forget about the 19 year old. Then did one turn 17 in 2020? You would lose it for them.
Your stimulus check is based on the number of qualifying people listed on your tax return for 2020. You don't receive a check for the new baby necessarily, it is just based on the number of qualifying people listed on your return.
So, if you lost one qualifying person because they turned 17 and replaced that person with a new baby, you still just have 8 qualifying children.
