TAX Return rejected due to Tax Returns field by my 18 year old dependent

[NCperson]

'child' is defined as a 'qualifying child in the CARES act, which are children under 17 years old..... So 'other relatives will not be eligible for the $500

[LeonardS]

There is no guidance at this time that specifically address your question.  Generally, the IRS takes 8 to 12 weeks to process amended tax returns, definitely longer than the time frame in which the stimulus checks will be sent. If you send in your amended return before the IRS process your son's return this may cause the whole process to be delayed beyond the normal processing time.