Yes, you will only input the amount you received which you mentioned was $2,800. You will not include the the checks your son received. If all the income and dependency criteria are met, you will be able to claim the stimulus payment for your child. However, you mentioned that you will get and additional $1,200. However, the third stimulus check which was received in 2021, was for $1,400 and not $1,200 so please make sure you verify the amounts.
