deleted wrong dependent

You can file an amended return and swap out dependents but it will take a long time to process. Once it is processed, your brother can file his taxes and claim the credit.

Once your return is accepted and the finances are settled, you can file an amended return. 

• Save a copy of the original return before doing an amended return. See: 
  • how to file an amended return.
  • I need to amend my state return.
  • Can I e-file my amended state return?
  • Can I e-file my 1040X to amend my return?
• Pay additional tax. Taxpayers who will owe more tax should file Form 1040-X and pay the tax as soon as possible to avoid penalties and interest. They should consider using IRS Direct Pay to pay any tax directly from a checking or savings account for free.
• Track amended return status online. Taxpayers can track the status of their amended tax return in English and Spanish using Where’s My Amended Return?  Amended returns take up to 16 weeks to process and up to three weeks from the date of mailing to show up in the system.