I have a similar situation, but wanted to file to take advantage of state savings.  However, in my situation there was TP, SP, and one dependent in 2020.  They had a baby in 2021 and received the $1,400 for three individuals.  The letter says each taxpayer received $2,100.  When I split the return and put both kids with the lower income earner to get under the threshold for child tax credit it is giving an extra $700 of Recovery Rebate Credit, so instead of $1,400, it is giving her $2,100.  The other taxpayer is having to pay back the advanced child tax credit, but of course is not having to pay back the $700 they received for the older child.  I found a link posted on one of these threads that said the credit could be up to $500 for the other parent, but that was in a divorce case.  Should I leave the $2,100 recovery rebate on the return, change it to $1,900 or only claim the $1,400 for the new baby?  It's still more advantageous to file separately regardless of which option I need to go with, but don't want to delay refunds for the client if possible.