Do I need to prove my return was rejected or will they know?

I meant the IRS. I cannot refile until my daughter amends her return. The little box, on her first return, was not checked to say she can be claimed as a dependent. SO ours was rejected.

When you amend your return, you can provide the explanation that you return was rejected.

Who is "they" you are referring to?    No, you do not need to prove.   To fix it, here are the instructions:

https://ttlc.intuit.com/replies/3302275