No, filing as Single with two dependents probably won't be rejected, although you can hope it gets rejected for another reason.
As you probably know, if your return is rejected, then you can re-enter the return, make changes, and e-file it as if for the first time.
But if the return is accepted, then you will have to amend your return either in a few weeks or when you receive your refund.
To learn more information on how to amend your return, please see this TurboTax FAQ: https://ttlc.intuit.com/replies/3288565
