Unfortunately, if you have already e-filed your return it is too late. Once you transmit your return you cannot change it or get it back. You would have to wait until your return gets rejected or accepted. If rejected, you can add your W2-G to your return. If accepted, you would need to amend your return to correct or add information to your return.
If you need to amend your return and you're amending to claim more money, the IRS says to wait until you've received your original refund before filing an amendment. Once you've received your original refund, feel free to cash or spend it while your amendment gets processed (this can take 12–16 weeks). 3 weeks after you mailed your amendment, you can start tracking its progress at the IRS Where's My Amended Return? site.
More information regarding amending a return can be found below:
https://ttlc.intuit.com/replies/3288565
Unfortunately, if you have already e-filed your return it is too late. Once you transmit your return you cannot change it or get it back. You would have to wait until your return gets rejected or accepted. If rejected, you can add your W2-G to your return. If accepted, you would need to amend your return to correct or add information to your return.
If you need to amend your return and you're amending to claim more money, the IRS says to wait until you've received your original refund before filing an amendment. Once you've received your original refund, feel free to cash or spend it while your amendment gets processed (this can take 12–16 weeks). 3 weeks after you mailed your amendment, you can start tracking its progress at the IRS Where's My Amended Return? site.
More information regarding amending a return can be found below:
https://ttlc.intuit.com/replies/3288565