I'll be confused. Your client claimed the child and attached the signed 8332 from the other parent, releasing the dependent to your client, and it was bounced?

Why, because the other parent already claimed the child, in opposition to the signed release 8332?

If the signed parent filed and claimed wrongly, your client has to paper file and provide support to prove that your client deserved the dependent, such as divorce decree and support agreement.

That still doesn't guarantee that your client will win. It won't be the first time someone claimed improperly.