Yes, there was a way to manually add that you and your kids did not receive the first round of stimulus through the Recovery Rebate Credit. But, since this credit was partially included in your return, you will not have to amend your return.
The IRS will adjust it. The IRS issued guidance March 1, 2021 regarding this situation. There will be a slight delay in processing your return.
2020 Recovery Rebate Credit — Topic G: Correcting issues after the 2020 tax return is filed
DO NOT file an amended tax return with the IRS. If you entered an amount on line 30 but made a mistake in calculating the amount, the IRS will calculate the correct amount of the Recovery Rebate Credit, make the correction to your tax return and continue processing your return. If a correction is needed, there may be a slight delay in processing your return and the IRS will send you a notice explaining any change made.
For more information, see: Recovery Rebate Credit Frequently Asked Questions | Internal Revenue Service
