I accidentally claimed my kids as dependents when their other parent should have. I amended my return today. Does the other parent have to wait until my amended return is processed before their return is processed and refunded?
No, they do not have to wait for your amended return to process. That may take 4 months or longer.
They can file now with the dependents on their tax return but they will have to print and mail their return since a tax return with the dependents SS numbers has already been received by the IRS. It they try and e-file the return will be rejected by the IRS.