You say it would be unethical but the IRS gives you no choice. They have specifically stated  the amounts from EIP letter 6475 and AdvCTC letter 6475 must reconcile with their records. In 2020 it was advantageous for a couple to file Married Seperately. The father claimed the only dependent son and received the EIP and AdvCTC payments. In 2021 it is advantageous for the mother to claim the dependent son. When the mother puts her info in, the software automatically gives her the $1400 EIP for the dependent because her EIP letter 6475 states $1400 and the full Child TaxCredit because she didnt receive any AdvCTC or a  AdvCTC letter 6475. There is no way for her to show the amounts the father received. If she adds them to her EIP letter 6475 or puts the amounts received on the fathers AdvCTC it will not reconcile with the IRS amounts and delay the returns. I also have a feeling the IRS may automatically correct the figures and add them to the refund. I know of people who forgot to take the EIC and when they got their refund the IRS had automatically added it in then sent them a letter a week later explaining what they did. You say it is gaming the system but there is no other choice.