You will need to wait and see if your return is accepted or rejected by the IRS.
If your return is rejected, then you can just go back and fix the errors (adding in your additional w-2s)
Use this link to learn why your return was rejected and how to fix it.
Click on each step for instructions on how to make corrections and re-file.
https://ttlc.intuit.com/questions/1901491-how-do-i-fix-a-rejected-return
If your return was accepted, then you can file an amendment.
If you need to file an amended return, you should use Form 1040X. For 2017 returns, instructions will be available in late January or early February 2018. You will have to mail in the amended Use this link to learn where to mail your 1040X: https://www.irs.gov/filing/where-to-file-addresses-for-taxpayers-and-tax-professionals-filing-form-1...
