@ovazquez61
For the 2020 return :
If you were qualifying dependents of your parents then they should claim you and the kids by mailing in an original return or an amended one if they already filed. Don't worry about what the father did.
For the 2021 return ... file it correctly and let the chips fly. If you don't get the CTC in advance the person claiming the child on the 2021 return will get the credit then.
